Geohazards in Bangladesh

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Finishing Up in Bangladesh

Sat, 02/24/2018 - 13:49

Céline proudly takes her gravity meter out of the shipping box. It felt like Christmas morning to her.

Humayun and I arrived in Sremongal and were reunited with the others. After dinner, the gravity meter that Céline will use for measurements here after we leave finally arrived, making Céline very happy. It had been stuck in customs getting clearance for days as she impatiently waited for it to arrive. As time was growing short, Céline suggested that we should split into two installation teams and each do one of the far northern sites. Alissa, Humayun, Sanju and I went to BN05 while Celine, Nano, Paul and Karim went to BN04. Both are

The good road to BN05. It is elevated far above the fields so it stays above water during the monsoon flooding.

2-3 hours away, but potentially longer if the roads are bad. Traveling through extensive fields of rice, the road was surprisingly good for someplace so remote and easily flooded. As was often the case, the scouted site was not good, so we called the chairman. While he wasn’t home, his brother was and after a long conversation with Humayun, offered his family’s home. It was large enough that there were several options, but one was clearly better than the others and we installed one of our smaller waterproof seismometers, just in

Humayun breaks ground for the sensor hole with a kodal, a cross between a hoe and a shovel that is great for digging.

case of flooding. We were now experienced and completed it in less than 2 hours. More tea and photos and we were on the long road back. Céline’s team was also successful; two sites in one day put us back on track.

We again split the next day, with Céline, Alissa, Humayun and myself going to install B9, while the others went to look at the geology in the hills farther east. along the way they also stopped off at a tea garden to scout BN01. B9, officially BA09, had already been scouted, so we

Posing for a group photo at the nearly completed BN05 site.

quickly installed and took pictures with the family. After that was done, we went to service some stations, collecting the few days of data to make sure everything was working well and analyze the noise levels at the sites. We stopped at B10, where the owner treated us to his boroi, small apple-like fruits. Then we went to B8 located at a manager’s house in a tea garden. We wanted to do B7 as well, but they had important guests visiting and did not want us to come by today.

Céline stays out of the sun while writing the readings when servicing a station.

The next day was our last installation in this region, the Sylhet Division of Bangladesh. We again split into teams for the final installation, for doing field geology, and for servicing. Karim and I did the service runs. We did B3, outside a private home, then B2 in a tea garden manager house. We only saw the 6 servants that maintained the property. As we left, Karim pointed out that he thought two of them were transgender. Next was the long hard drive to B1. As we came close we called the manager to

Opening the equipment box at B8. They constructed a nice bamboo fence for the site.

ask about sending his jeep to drive the last stretch of road. However he had guests, so we had to walk the last mile to the tea garden. Along the way, we passed crews fixing the road. This time, we were invited to join his guests for tea and cookies in the gazebo when we finished. It was very welcome after the long walk in the hot sun. While we were having tea, our driver showed up. They had finished fixing the road sufficiently for our van to come up. The next people to visit for servicing will appreciate that. We ended the day servicing BN03 as B4 was also

Posing with the extended family of the people hosting the site at B9. The box is kept in the house for safety.

having important visitors at the tea garden. We got back before the others and then went for a final dinner together.

The next morning, Humayun, Alissa and I headed to DUET in Gazipur, where we started this trip. We met Jim’s team and put all the empty boxes into storage. Then we dropped Jim and Alissa at the airport, while Chris and I dove into Dhaka. My first time here this trip. We have the final station to install in the morning and then we fly out the next

Our team leaving B9 after another successful installation.

day. Nano and Paul and Sanju will do geology for a few more days then meet us in Dhaka. Nano flies out with us, Paul heads to India the next day. Céline will continue to stay in Srimongal doing a gravity survey with Karim for the next week.

The last station is south of Dhaka between the Dhaleshwari River and the Padma, the combined Ganges and Brahmaputra. It is at a health service complex. We met and had tea, then

Me posing with the staff of the manager’s bungalow during the service run.

looked around the grounds for a good site. The first were vetoed as not secure. Too many drug addicts near the clinic. Finally we found a good spot in the open near some people’s homes, including the night security guard. It went quickly and in the middle they climbed a tree and got us some fresh green coconuts. Coconut water is very refreshing on a hot day. We finished, but not earliy enough to visit the Padma. We still had to store the remaining equipment at Dhaka University. It has been a very successful

Kids watch us service the station at BN03. This site had the sensor indoors.

trip. As is my experience here, people find a way to get done what needs to be done. It is a country that is resilient out of necessity. We have installed 6 GPS, 28 seismometers, Céline is getting gravity measurements that have help up a project, and Paul has at least one good geological transect across an anticline with a few more days of work. Some of us have been working together for years, but others are new to our group and Bangladesh. Over 3 weeks in the field together will help change us into a team.

Sam, myself and Chris drinking green coconut in a selfie by Muktadir, who joined us for the day.

Céline in the truck helping to unload the remaining equipment.

Sanju buying bananas and Bangladeshi snacks like singara and piagju

Installing the seismometer array

Thu, 02/22/2018 - 08:47

Jim, Chris and myself being hosted at the original scouted site for B11. We were served tea along with grapes, pomegranate, and oranges.

I spent two more days with Jim’s team. The first day we went to scout two of the sites and then install one that was already scouted. Humayun had sent a team of students out to scout the 28 seismometers we were installing, but some of the sites were good and some were not. B11 was too close to the highway and without an out of the way place with a good place for a solar panel. After tea and fruit, the owner walked around the village with us and we found a better site. It was at the edge of a yard next to the cow shed and at the edge of a slope. The family was ready to host it

View of channel will boat through the trees on the walt between the site and the car. During the monsoon, it will be used to get around.

there, so we moved on to Scout B12, the one site that was not scouted. I could see there were no roads to where I have located the site. I chose a new place as we tried to drive to it. We went as far out on the road as we could drive and started talking to people. We met the local chairman and walked around with him. There were a couple of larger, more elevation homes and we went to one and discussed it with the family. They were positive, but would make a final decision tonight.

We went on to B13, already scouted, to

Walking through a village looking for a place to put the seismic station.

install. It was on the other side of the Meghna River. We unloaded our gear and got ready, but the family backed out. He thought the installation was for 2 hours, not 2 years. We went looking for a new site. First locally, then driving a little farther afield, then as a school but we struck out. It was the end of the day and we have not put any seismometers in the ground.

The next day was better. In the morning we went to install B11. When that was

Chris in the seismometer hole at B12. It is the larger hole for the sensor that needs a “vault” – the blue barrel in the background.

done we decided to try a different road for B12. We went out on it as far as we could and beyond that point there were no homes. We turned around and stopped at every house to inquire about putting a seismometer there. Actually, Sam did and without speaking Bangla, there was little we could do. Some weren’t interested or scared of the equipment, some had no good location. After about a half dozen homes, we waited outside one promising place, but the owner wasn’t home. Finally his brother said we could put it at his house.

Sam discussing the installation with the person whose house we eventually used.

Not quite as good, but it was a bird in the hand. That night Humayun and Sanju arrived with Paul, who flew in to see the geology on the way to NE India. After dinner, Paul and Sanju went east to join the other team, while Humayun joined ours.

The next day, Jim, Chris and Sam went build a fence at B11, while Humayun and I went to scout. I felt that with the problems both teams were having as some sites, we might not be able to finish

Chris waiting for the deliberations to finish with a flock of kids.

on time. Adding a third team for scouting would help save time and let the other concentrate on the actual installations. We went to the government building for B10. When it turned out to not be good, we went to the local chairman and he ended up offering his house, an excellent site. Then it was time for B13 once again. We tried on the other side of the Old Brahmaputra River. The Brahmaputra shifted about 60 mi west of here about 200 years ago leaving a smaller river and a broad low area with rice fields and

Some of the rice fields that surrounded us in this particularly, low flat part of Bangladesh .

brick factories. We took smaller and smaller roads, ending in a heavily rutted dirt road. We saw a government building that looked good, but it was locked. We talked to the neighbor and decided to put the instrument there. Not an ideal location, but after 2 days of failed attempts to get B13, we took it and headed east to join the other seismology team, stopping to say goodbye to the team finishing up B10.

Jim tries to talk to an older neighbor while waiting. However, neither speaks the other’s language

The completed station at B12 with the wire mesh fence protecting the buried sensor. The box is inside the house.

Sam on the roof securing the solar panel while Razzak holds it in place with a bamboo stick.

Our car and truck on the road past B12. It is elevated to prevent flooding during the monsoon with rice paddies on either side.

Transition to Seismology Scouting

Sun, 02/18/2018 - 12:12

A Bangladeshi breakfast: paratha (bread), mumlet (egg), bhaji (vegetables), moog dal (mung beans).

With the scouting done, we just that the installation of the final two GPS sites to do. Since we started drilling the hole for the antenna rod at Kalenga, we went there first to finish the installation. This time, the new road surface had dried enough for us to go over it. We arrived and went to work, becoming an experienced team for the installation. As promised, they had built us a ladder, a rickety one, but functional. After competing the job, we were surrounded by kids when we returned to the ground from the installation. We once again

Looking down on Sanju and Keith installing the grounding rod among schoolchildren.

handed out chocolates to all the students and teachers, had tea and went on our way.

It was still afternoon, so we drove to Chunarughat where the seismic team had just finished installing a station in the college where we reoccupied. We all had tea, some fresh pineapple, snacks and caught up. They went off to another site, while we went to scout two sites farther along that were on tea plantations. We had had problems

Handing out chocolates to the students at Kalenga.

getting permissions as some were large corporations with headquarters in Dhaka. We headed to the first one, the Chundeecherra Tea Estate. We found the office and explained the situation. As first we were dismissed, but Sanju persisted, making friends with the assistant, who called the manager back and we were invited to his bungalow. We went there and discussed the project, and had tea and snacks. The Tea Garden and bungalow – a term meaning a house in the Bengali style – date from 1876. He

Having an afternoon tea with the manager of the Chundeecherra Tea Estate.

needed to confirm with his higher ups in Dhaka, but had been won over to allowing our deployment. In fact, later we received approval to place seismometers in any Tea Garden belonging to the National Tea Company.

He directed us to the next Tea Garden, although we got lost before finding the right place. While we call these places Tea Gardens, they can be miles of tea plants in every direction, major operations to run. We had trouble

A CNG on the bad road to Kalenga.

finding the correct entrance. We again showed up at the manager’s house and were welcomed with tea and snacks. Sanju did his magic again, making friends and persuading him to allow us to install the seismometer at his bungalow. This tea company is privately held and the manager gave approval pending confirmation with the owner, his uncle. A productive day.

A buffalo on the way to the last station.

The next day we went back to install the last GPS station, again bringing chocolates for the students. The drilling was slow as the concrete was hard and the batteries didn’t last. We sent our driver to recharge them at the nearest town with electricity.

He went with the principal on his motorcycle. After finishing the job we took our last group photos and had tea and cookies with the teachers.

The brightly colored walls of a classroom with a scene from the 1971 War of Independence above “Rain Rain Go Away”

Again we went to stop at a Tea Garden for permission. This was at Finley’s a large multinational company. We were turned away at the gate. Sanju did not give up. He persisted and argued with them for a long time, although it seemed fruitless. He then tried going above them calling the local chief of police and elected representatives. He would not give up. Eventually the assistant manager came out and spoke to us. We explained our situation. He had previously spoken with the scouting team. He agreed that we needed to speak to the Chief

Sanju attaches the batteries on the roof while a teacher gives the class an outdoor lesson in English.

Operating Officer of Finlay. He would be in the next morning at 9. We had succeeded in getting out foot in the door thanks to Sanju’s determination. And with all of the GPS stations completed, we could turn our full attention to scouting the seismic stations for the one day before Keith leaves to return to the U.S.

The next morning we arrived and were let through the gate. We drove to the COO’s office and waited until he was free. Again we explained what we were doing, reassured him, as the others that the seismometers only listen to earthquakes from around the world. They do not interfere with anything or cause earthquakes. His concern was not being able

After finishing the last station, the three of us posed together on the roof.

to provide security to watch the instruments, but we reassured him that we usually left them unattended. He tentatively agreed pending some paperwork. We headed to the offices of the managers of the individual Tea Gardens we would be installing in. We drove past miles of tea to the first. When we showed the manager to location, he pointed out that it was not in Finlay’s but another Tea Garden beyond their property.

We were served tea at the front of the school.

We headed off farther into the hill. The roads got progressively worse, although the road cuts showed some good geology. Finally, we hit a rut we could not drive through and walked the last mile. After waiting for him in the gazebo to finish his shower, we again had tea and snacks. We got an agreement and chose a site in his yard next to the satellite dishes (after reassuring him it would not affect reception). Another site successfully done. We walked back and then got a ride the last part of the way

Crowds of kids followed us as we packed up our van to leave.

from his jeep, carrying the head of another tea company. We drove to the other site on Finlay’s property, but the manager was not home. He would be back in 2 hours at 4. We left and went to pick up some gift bags of tea that Sanju’s father had left for us. It was on top of the next anticline. After several wrong turns, and more cups of tea, we got our packages. It had only taken an hour and a half to get there. On the way back, we got a call from the manager, he would meet the COO tonight to discuss the seismometers, so no need to come today. We had done what we could today. This part of the trip was a success.

Finishing the GPS Scouting

Wed, 02/14/2018 - 13:12

The electric auto rickshaw we took out to Dolucharra to finish up by securing the box

After the drive yesterday, it was clear the car needed fixing.  No need to rush out early in the morning and I got some much needed sleep for my jetlag and my cold.  After a later, for us, breakfast, Bulbul, our driver took the car to be fixed.  We took an autorickshaw to the first site to add the chain and lock security system and see the sky view without the trees.  This time we had neither a ladder nor a truck to climb on.  Keith and Sanju scaled the building, but I was still shaky from the cold and stayed

Sanju scaling the school building to get to the roof. The overhang made it tricky.

below.  I worked on my blog until I ended up showing a group of kids my photos.  That was where I was when they found me after completing the short job. My choice to stay down was reinforce by learning that Sanju had fallen on the way down.  A pice of the concrete roof had broken off in his hand and he fell backwards onto the cut down tree.  Luckily he was OK.  His glasses frame was broken, his elbow banged up and had a some scratches from thorns, only minor injuries.  With the car still being repaired,

Showing the kids at the school my photos of them, Bangladesh and the world.

we had some enforced free time.  We went to a famous shop outside of Srimongal past a rubber tree plantation, where they serve 7-layer tea. In fact, this was where it was created.  Carefully pouring (I presume) they float 7 distinct layers of different colored teas on each other.  Refreshed, we headed back to wait for the car, and Keith repaired Sanju’s glasses.

It was too late for an installation that was

A grove of rubber trees that we passed on our way to tea.

an hour drive away, so we turned out attention westward. We were reoccupying a site at a College (high school) in Chunarughat, but we also had one more place to scout. This one was to be co-located with a seismic site, B4. The advance team found a home, but it would require constructing a monument.  We went to see for ourselves if it would work for us, passing one of the two seismic teams joining us in Srimongal – Nano, Céline, Alissa and Karim.  A few minutes of greetings and

Keith sips his seven-layer tea.

we were both back on our way. Driving across the rice fields, with a few wrong turns, we found the direct road had a bamboo bridge we could not cross.  We had to double back and take a longer more roundabout route ending with bumpy dirt roads that were not meant for cars.  Finally, we hit another bamboo bridge less than a kilometer from the site.  We walked there and met the owner of the house.  It would be usable

We briefly crossed paths with one of the seismic teams at the statue of a woman picking tea on a hilltop.

for seismometers, but there was no open sky view for us.  We walked another kilometer farther, but this time we had no luck.  The school was surrounded by trees. We were told that there was another school at a place called Kalenga with no trees.  By now it was dark, so we headed to the dinner with the seismic team. They were having a more difficult time.  Permissions were not finalized and appeared to be harder to get.

 The next day we went to Chunarughat to do the reinstallation.  I have been here a few times since the initial visit in 2007.  The last time, I saw the antenna, it was loose and assumed it was a problem with the mount.  Instead, it was more serious.  The rod itself was loose and had rotated.  2 silver threads on the rod were visible

On the roof with the redone monument, solar panel and cable.

beneath the green weathered ones. Looking at my photos we pieced together that the antenna cable came loose and the straightening of the loops to relieve tension had rotated the antenna 1.5 times so the north end was pointing south. The unscrewing created a 3.5 mm increase in the height of the rod. I will have to look at the data carefully to see if we can figure out when it happened and correct it.  Keith then carefully unscrewed it, added a really strong epoxy and screwed it back to its original level.  Sanju and I took rickshaws into

Sanju took a selfie of us in the rickshaw.

town to buy more electrical wire for the solar panel and for grounding.  After a while, Chunarughat was up and running again.

 After some tea and snacks, it was time for the last task – finding the final GPS site. We went off in search of the now mythical Kalenga.  I didn’t understand why everyone we asked seemed to know the direction to Kalenga until I realized there was a Forest Reserve of the same

A college assistant did his spiderman imitation to help us get the solar panel cable installed.

name.  We continued along progressively worse roads until the colorful school at Kalenga appeared.  It was indeed open, surrounded on two sides by rice fields.  Although it was on the anticlines, the rivers eroding it had created valleys suitable for rice will into the anticline.  The school principal quickly agreed to the installation.  We didn’t have more equipment with us, but we had the drill.  That would save us some time tomorrow, so we drilled until the power ran out of the batteries.  None of these schools had power, so instead of the large drill, we had to use the smaller battery powered

Posing with the reporter (to my left) that came out to interview us while we were drilling at Kalenga.

one.  We had been needing to recharge the batteries to do all the drilling, but with this early start, perhaps we would not.  In any case, sites for all the GPS had been located and arranged.  All that was left was the mechanics of the actual installation for the last two sites.

Giving out chocolates to the children at Dolucharra to thank them for the use of their school.

Primary Schools to the Rescue

Sun, 02/11/2018 - 12:46

Up ahead on a hill was the brightly colored primary school, perfect for a GPS installation

We headed to the next area. One of Humayun’s students scouted for a location and found a reinforced concrete building, but it was not on the anticline as I wanted. It was farther west on the flatter land adjacent to the hill. It was on the wrong side of the rice/tea transition. We met the owner of the property and he accompanied us as we searched for another place. We could see why he stopped. Farther on the driving was more difficult and the houses were all thatch and tin. Walking around, we were shown a reinforced concrete building

Lifting the solar panel up to the roof for installation. To get to the top you have to climb from the ladder to the window ledge to the roof.

under construction, but it wouldn’t be finished for 2 years. We kept hunting and then we found it. There, in a clearing, was a brightly colored primary school. Again, the headmaster quickly agreed to let us install the GPS on the roof. I even was presented to the classes. The students are a mixture of Bengali, Khasi and Garo. The later two are groups that are mainly in the eastern and western Shillong Plateau (Meghalaya). We are finding that many of the villages in the hills are part of the 2% of the non-Bengali population of Bangladesh. The Bengalis like the plains and rice farming, the others are hill people growing other crops. The Khasi here are Christian, we passed a church on our way in. Later we met their tribal leader.

This time a short ladder was found, allowing us to climb to the ledge over the window and then onto the roof. Much easier going up than going down

“High” tea is served on the rooftop.

with the roof overhang. We again went to work, drilling holes in their roof and mounting the antenna, the solar panels and chaining the receiver box down for security. They had no electricity so we had to use the cordless drill until it ran out of power. Then we had to send our driver to the closest village to recharge them. Meanwhile, they served us tea and cookies on the roof. We couldn’t quite get the antenna rod as far in as I like, but plenty for stability.

Keith with Sanju attaching the antenna wire

The next day we had another site in a building that was too far from the hill. Again we went forward into the hills. This time, however, there was no local school. One of the Khasi villagers showed us around, but even the open fields had too many tall trees around. The best we could find was the corner of the rice of our guide. He would sell us the little plot of land we need, but it would be expensive since it would permanently removed it from productive rice farming. Sanju pointed out that there were some

The chain and lock system we devised to attach the GPS to the roof for security and the monsoon

Manipuri villages to the south, so we went back to the main road to try them. We discovered the maps of the area were not accurate; we failed to get to Islampur. We tried some other roads farther south. Our car could not make the direct route, so we took a detour that led us into dirt roads through a tea estate. It led us off in the wrong direction and our van was sounding worse and worse. It sounded like the CV joint was failing. We circled back to the main road on an unmapped road. We picked up someone who would show us how to

Our guide showing us possible GPS sites

drive to Kolabonpara, our last option to the south. Beyond that is India. Again, there were no local concrete buildings. The best we could find was a newly planted field of tea. Since the tea is kept waist high, we could put the monument in the middle of the field. However, the only way to get to it was over a bamboo bridge. It would be very difficult to get a welder and generator over that. We took the name and phone number of the

One of the many bamboo bridges we crossed, but our van could not.

manager, who was away in Dhaka, and headed off. On the way back north, we decided to make one last try by going to a village north of where we started. We got most of the way there and found a newly rebuild section of dirt road. It was too soft for the van, so we walked the final ½ hour to the village. We went passed the rice fields in through the beautiful woods next to the first high hill. Finally at the end, we saw it, the land opened up and there in the clearing was another brightly colored reinforced

Sanju and I search for the best way to go using my phone for directions.

concrete school. Since it was Friday, it was closed, but we got the name, address and phone number of the headmaster and went off to meet him. He turned out, not only to be Manipuri, but to also be Sanju’s “uncle”. Our hotel. With permission in hand, we headed back to our hotel. Scouting had taken the entire day, but we now had a location for the next GPS.

Working through the woods towards what turned out to be another good school.

Meanwhile, the seismology team did their huddle test – assembling all 30 instruments to test them.

Installing the first two GPS sites

Fri, 02/09/2018 - 21:26

While driving looking for sites, we passed several elephants – the local cranes for lifting heavy items.

Unlike the GPS in your car or phone that gets a location to about 10 feet, the much more expensive systems we are putting in will get daily position estimates to about 2 millimeters. To do that, they need a clear view of the sky in all directions. We have two options for mounting the GPS antennas. If we can locate solid reinforced concrete buildings, we have cement a stainless steel rod into one of the columns. If not, we can build a braced monument out of vertical and diagonal stainless steel rods driven into the ground and welded

One of the lemon trees at Lemon Garden

together to make a solid base. We came prepared for either. The first can be done in a day, but the second will need at least two days and finding a local welder. This part of Bangladesh has the sediments folded up into linear hills where they grow tea and broad flat valleys where they grow rice. We will put 6 GPS on different parts of multiple hills and valleys.

Walking through the grounds of Lemon

Carrying the freshly cut pineapples down the hill.

Garden in the morning fog, there were no appropriate buildings and no sufficiently open space. We did find their grove of lemon trees (actually limes). We considered a hill nearby, but there was a tree at the top. As we saw later, the slopes are planted with pineapples that were being harvested. If fact, the hills here are either heavily forested or covered in tea. The tea plants are kept short for ease of picking leaves, but trees are scattered among them. We headed over to my backup for this area, a village

Climbing up the truck to get to the roof. We always have interesting ladders in Bangladesh.

nearby where perhaps there will be some homes, government buildings or schools that are suitable. As soon as we got to the village, we saw the local school. It is the only reinforced concrete building in the village. It   seems promising, but there are some trees around it that block the view. We met with the school officials and amazingly they agreed to cut down the trees. However, we needed final permission from the Upazila (county) Education Minister. We drove down to Srimongal, and got our permissions, along with cups of tea and cookies. It is amazing how accommodating the Bangladeshis are to us.

Our next hurdle was a ladder to the roof. When none was found, used the truck as our ladder, climbing onto its roof and then the building’s. It was now the afternoon, so we quickly went to

Keith drilling the hole in the reinforced concrete column for the antenna rod.

work, drilling an 18” hole in the roof and epoxying in the rod for the antenna, assembling the solar panel frame and attaching it to the roof, and finally setting up the waterproof box that will hold the GPS, the batteries, and the modem that will send the data to UNAVCO in Colorado. While we were working, the woodcutter arrived. Sanju is an ethnic Manipuri from the others side of this hill or anticline. He used his contacts to find a woodcutter, who arrived along with his uncle and younger brother. His tools

Sanju watches the woodcutter work on the tree.

were a machete and a rope. Because we needed two trees cut down and he needed to avoid a nearby home, he raised his price. In the end, it cost us 1400 Taka, almost $17, a tiny fraction of the cost in the U.S. Part of the tree falling killed a lemon tree, so we will have to pay the owner for the loss. Sanju is still negotiating the terms. As is almost always the case, it was dark before we finished the last part, installing the grounding rod for lightning protection.

Keith and Sanju wiring batteries in the receiver box. The receiver is the black and orange rectangle mounted vertically.

The next day, we traveled two and a half hours to our farthest site. This is a reinstallation of one be installed in 2007. The GPS, borrowed from UNAVCO had to be returned in late 2016. That makes this a simpler installation as the rod and cables are already in place. It is in a medical clinic with the equipment box located in the birthing room. The people I had met in 2007 have moved and there is a new doctor and his family living in the clinic. Since 2007, a number of trees have grown up. We again need to have trees cut down. Sanju negotiated with

Sanju watches Keith finish the installation while leaning on the birthing table with medical equipment behind.

the neighbor and she agreed to cut the tree for a fee, which she will sell for the wood. The branches of another tree will be cut back once the boroi fruit, like miniature apples are collected. Lunch was again tea and snacks. Two days and two sites installed. After delays of a few more days, the seismic group finally got their equipment and started testing them as we finished the second site. Things are going well for us.

One of the trucks bringing over 2 tons of seismic equipment to DUET

Fellowship of the Seismometers

Thu, 02/08/2018 - 12:55

I am back in Bangladesh to start the deployment of equipment for a large new project. Results from our last project showed there is a large earthquake hazard here. We demonstrated that the Sumatra subduction zone, where India plunges beneath Asia, continues to the north under Bangladesh. The subduction down at Sumatra caused the 2004 earthquake and tsunami that killed over 230,000 people. Even though the plate boundary comes onshore, unusual for subduction zones, is it still active with the world’s largest pile of sediments, the Ganges-Brahmaputra Delta, entering it. We have designed an experiment to investigate this plate boundary across 3 countries: Bangladesh, India and Myanmar.

A map showing our planned deployment of seismometers in Bangladesh (red), India (blue) and Myanmar (green). The heavy black and gray lines are the major and secondary faults. The GPS we are installing now are in the box labeled DET.

Our first step is to install 29 seismometers and 6 GPS receivers in Bangladesh. To do this, we have a team of 11 people. Most of us will be here for three and a half weeks. There are five of us from Lamont, two engineers from PASSCAL and UNAVCO, organizations that provide support and equipment to NSF projects like ours, and four from Dhaka University. Ahead of us, we shipped over 2 tons of seismic equipment and carried over 300 lbs. with us on the plane. Thanks to a 2 hr. delay due to fog in Dhaka, our flights lasted a full 24 hours, longer for the two engineers coming from Colorado and New Mexico. We then spent the next several at the airport getting all our luggage, getting them through the huge backup at customs from all the delayed flights, changing money and getting local phone numbers.

Keith, Alissa and Jim trying their first Bangladeshi meal.

At a lunch stop, 4 members of our team who have never been here before tasted their first Bangla food. So far, they are all enjoying it. We then arrived at the Dhaka University of Engineering and Technology (DUET), north of that city to set up our base.

When we arrived we found out that the seismic equipment is being help up by customs. Since the packing list mentions antennas, the GPS antenna that gets exact time for the seismometers,

Our group: Karim, Samiul, Jim, Alissa, Keith, myself, Chris, Céline, Nano, Humayun and Sanju.

customs referred it to the Telecommunications Regulatory Commission. Humayun went back to Dhaka and spent the day there dealing with it, while Alissa and I tried to find the documents he needed to show the antennas only receive signals and do not cause not interference. The paperwork is slowly going through the bureaucracy and we hope it will be released tomorrow. Meanwhile, we spent the time running around Joydebpur shopping for the materials we need. The seismologists need to build underground vaults to hold

Jim and Nano arranging for the thick tiles that the sensors will sit on to be cut to size. The tiles will be used instead of a concrete pad, saving time.

the instruments, while the GPS team needed grounding rods and wire. Most of seismic supplies bought or ordered, so they should be ready to move out ahead of schedule even with the delay, if they get it tomorrow. The GPS team finished our shopping so tomorrow we will pack up, hopefully be able to fit everything in one van and take off. It will be Keith from UNAVCO, Sanju from Dhaka University and myself. When they are done shopping and testing, the seismic team will split into two 4-person groups for the installations, starting with the dense central line of stations. We will hopefully

Meeting with the president of DUET

see one of them by the end of the week when they arrive in the Srimongol area, where we are going. The other team will initially work from here at DUET. These are the two ends of the dense lines in Bangladesh and they will spend the following week deploying towards each other.

Of course we had too much stuff for the van, so the truck will come with us to carry our equipment than then return to

Tea plants covering the hills of Sylhet. They are trimmed low to make it easier to pick the tea leaves.

DUET. He had the mandatory meet and greet with the president of DUET. In the end our leaving first thing in the morning stretched to 12:30. We had hoped to stop at one of the sites on the way, but instead we went straight to the Lemon Garden Resort in the hills near Srimongal. The hills in Sylhet, the NE part of Bangladesh are covered in tea estates. There are a growing number of resorts in the hills as well. Lemon Gardens has beautiful grounds and tomorrow we will see if there is a good spot for a GPS.

Sampling on the Ganges and Brahmaputra Rivers

Sat, 02/04/2017 - 21:51
Chris smiling broadly as he and Humayun buy 11 lbs of Jordibaja, a local Kushtia snack food from the most famous bakery that makes it.

Chris smiling broadly as he and Humayun buy 11 lbs of Jordibaja, a local Kushtia snack food from the most famous bakery that makes it.

From Khulna in the SW, we are heading to Rajshahi on the Ganges River, but first we are stopping at Kushtia, Humayun’s home town. Because the road on the more direct route is supposed to have bad road conditions, we took a longer route, way longer. It wiped out any chance to get to Rajshahi in time for some fieldwork, but it did my districts (states) of Bangladesh visited to 40 out of 64. After many hours on the road, we reached Kushtia and out goal – jordibaja, a fried noodle snack that is only available here. Chris bought ten 500 gram bags, about 11 lbs, at the bakery that makes

Liz in Rajshahi walking back to our group protected by two policewoman that were part of our escort during a quick visit back to our van.

Liz in Rajshahi walking back to our group protected by two policewoman that were part of our escort during a quick visit back to our van.

the best, of course. We then had a late lunch and continued to Rajshahi where we were once again joined by a police escort. Different teams stayed with us until we left the area. After finding our hotel, we all had our first hot water shower since we left Dhaka. Living on boats is great, except for the complete lack of hot water. Once cleaned up, we went to Humayun’s sister for a delicious dinner. After dinner, the commissioner of police, a former student of Humayun’s stopped by. He suggested we visit some of the chars (sandy river islands) close to Rajshahi rather than the places we went

Our police escort watches Chris and Dan measuring spectra on a char (sandy river island) to compare with satellite measurements.

Our police escort watches Chris and Dan measuring spectra on a char (sandy river island) to compare with satellite measurements.

to other years, an hour or more drive away. Chris and Dan checked their satellite images and found that the nearby chars would work, probably dsaving 2-3 hrs of driving.

The next morning, we headed off with out new escort, that included two policewoman. However, that had to switch off when we crossed from one precinct to another. Renting a country boat we crossed the Ganges to the chars. While Dan and Chris (with Humayun) made salinity, moisture and spectroscopic measurements, Liz and I

Dan measures the water content of a small area of quicksand we found while Liz is being sucked in as she explores it.

Dan measures the water content of a small area of quicksand we found while Liz is being sucked in as she explores it.

scouted for the proper sediment samples for her OSL needs. After wandering about the island we found what she wanted and collected a sample. Until now, her studies of the delta did not have any samples from the Ganges itself. For Dan and Chris to get the observations they wanted, we visited several chars before ending up back at the first one for them to study the transition from sandy sediments to rice fields. As soon as the chars have deposits of the right kind of sediments, people start planting crops. If the char continues

Digging out our OSL dating sample of silt on the Ganges. The tape wrapped PVC pipe had been hammered entirely into the outcrop. The sample inside must not be exposed to light or it will be ruined.

Digging out our OSL dating sample of silt on the Ganges. The tape wrapped PVC pipe had been hammered entirely into the outcrop. The sample inside must not be exposed to light or it will be ruined.

to grow and stabilize, they will move there as well. They are great places to live 9 months of the year, but a struggle during the high water of the monsoon season. The islands with migrate, eroding from one side while sediment deposits on the other. The char people have to move frequently as the chars move out from under their homes. Liz and I wandered off and found another place to sample. Now she have both a sand and a silt samples from the Ganges. It only took a few hours to accomplish the more specific tasks of this field program. When we first started visiting chars 12 years ago, we explored then from the morning

Chris and Dan discussing notes on locations to visit based on recent satellite images and entering them into the GPS.

Chris and Dan discussing notes on locations to visit based on recent satellite images and entering them into the GPS.

until dusk. We needed to see and explore all aspects of this new environment for us. Now, we are building on our work with much more focused activities.

Off the river by early afternoon, we drove across country to Bogra near the Jamuna River, as this part of the Brahmaputra is known. We were able to arrive around sunset, avoiding the sometimes frightening driving in the dark. For old times sake, we skipped the new hotel that was booked and stayed at the colorful Parjartan Hotel that we first used

Chris, Dan, and Bulbul, our driver, walking down the embankment at Sirajganj. During the summer, the water level will reach the top of the embankment as the river flow increases by a factor of 10 or more.

Chris, Dan, and Bulbul, our driver, walking down the embankment at Sirajganj. During the summer, the water level will reach the top of the embankment as the river flow increases by a factor of 10 or more.

in 2005. It is literally painted the colors of the rainbow, as well as having more character, even if everything is not quite working. This was the hotel where my room once had electric outlets of 4 different shapes, requiring every adapter I had to recharge my equipment. Now I always bring an outlet strip so I only need one adapter.

We had planned to go north to Gaibandha, but a new satellite overpass showed that we could get all the data we needed farther south at Sirajganj. We could cut out a day. As it turns out, this was fortuitious. I have a family

Humayun walks to the country boat we rented at Sirajganj to bring us across the river to the chars.

Humayun walks to the country boat we rented at Sirajganj to bring us across the river to the chars.

emergency and have to return to the U.S. From Sirajganj we could return to Dhaka, rather than stay at Tangail. Chris and the others can do the rest of the field work as day trips from Dhaka. It is more driving for them, but will enable be to catch the evening flight back to the U.S. We packed up and headed to the embankment at Sirajganj, which protects the city from the shifts in the Jamuna River. We walked down the embankment (the river level is about 7 m or 23 feet higher during the summer monsoon season). We headed for a large char that

Liz examines an outcrop on the large char across from Sirajganj while looking for appropriate sediments to sample. Wherever the conditions are right, the chars are planted with crops while the bare sand remains exposed in the younger parts of the char.

Liz examines an outcrop on the large char across from Sirajganj while looking for appropriate sediments to sample. Wherever the conditions are right, the chars are planted with crops while the bare sand remains exposed in the younger parts of the char.

we first visited in 2005. It has grown and become attached to other chars. It also has much more agriculture, they are growing rice, peanuts, lentils, corn and more. The complex history of changes in the char provides lots of different sediment types for Chris and Dan and plent of cut bank surfaces for Liz to get a good silt sample. A few hours of exploring, sampling, measuring and we were done. Since it is Friday, the Muslim holy day and the weekend here, traffic is light until we reach Dhaka. Near the university and our hotel, the streets are packed with people and rickshaws. Still we manage to get to the university to drop off equipment and for me to get 7

Liz measures the position of the hammered in sampling tube before we dig out and collect our last sample, a silt from the Jamuna (Brahmaputra) River.

Liz measures the position of the hammered in sampling tube before we dig out and collect our last sample, a silt from the Jamuna (Brahmaputra) River.

GPS receivers that finally have to be returned to UNAVCO after 10 years. This is the last of the 11 we were lent in 2007 by them. They provide geodetic data and services for NSF and allowed us multiple extensions that enabled us to get this much needed data for so long. It is the basis for our paper on the potential earthquake hazard in Bangladesh as we can see the slow motion of the surface (0-17 mm/y) that indicates the buildup of strain in the earth. Then back to our hotel to meet Dhiman and have a final dinner together before an Uber takes me to the airport. It is sad to leave early, but I

A local farmer shows Liz the peanuts he is growing on the char (behind them). Peanuts and lentils are common winter, or rabi, crops on the higher, drier parts of the char. The freshest peanuts we ever ate.

A local farmer shows Liz the peanuts he is growing on the char (behind them). Peanuts and lentils are common winter, or rabi, crops on the higher, drier parts of the char. The freshest peanuts we ever ate.

am needed at home and they can carry on without me for the last few days. They will visit the confluence of the Ganges and Brahmaputra Rivers, and the Padma, as the combined river is called. For me, my critical goals for this trip were accomplished.

Side trip to Hiron Point, Sundarbans

Tue, 01/31/2017 - 10:32
Our group returns on the country boat, the M.V. Sundari, from their morning fieldwork.

Our group returns on the country boat, the M.V. Sundari, from their morning fieldwork.

My critical equipment repairs were now done. Chris and Dan still had several days of work in the area, but Humayun and I were interested in traveling to Hiron Point near the coast in the Sundarban Mangrove Forest. We want to take advantage of being so close to We hoped we could do it in a day, with the tides and broad open channel to the south, it would take two, too much for Chris to spare. We worked out that Humayun, Liz and I could take Bachchu’s smaller boat, the M.B. Mowali. Mowali are the honey collectors in the Sundarban and Bawali are the wood cutters.

Chris measuring the reflectance spectra of the ground while some local woman look on.

Chris measuring the reflectance spectra of the ground while some local woman look on.

Before we leave, we have one day with Chris and the others. After, Matt and Tanjil, our forest guide from 2015 who stayed with us for a day, departed, I went out with them to Polders 32 and 31 for their afternoon run. They are making soil salinity measurements to see if it is possible to determine soil salinity from satellite imagery. Saline soils are a large problem in this part of Bangladesh. We took the country boat to shore and scouted for the appropriate place. At each one Chris and Dan laid out a grid of probes to measure salinity and moisture

Dan measuring the salinity of the soil.

Dan measuring the salinity of the soil.

content. Kingston and Zahan did similar measurements at the surface and at the root level. As always, we attracted a crowd of onlookers curious as to what these foreigners were doing.

Later, after dinner, the M.B. Mowali arrived and our group split once again. We traveled to the edge of the Sundarbans that night, to pick up our guide and our armed guard for the tigers. The Mowali is much smaller. I

Chris providing a detailed explanation of what he is doing in English to people who only speak Bangla.

Chris providing a detailed explanation of what he is doing in English to people who only speak Bangla.

haven’t seen her since she was renovated. Now there is one cabin, which Liz got, and a larger room for Humayun, myself and our guide. In the early morning we headed south. Once the fog lifted and we entered smaller channels, we started seeing deer and monkeys on the banks and in the forest. We stopped in a small side channel and had lunch before crossing the over 10-km wide estuary in our speed boat, a 40-min ride. I could see that a lot on fresh land had grown at the mouth of the channel with the forest station and our GPS since the

Liz gets photographed with two young girls. Blonde women doing field work is not that common here.

Liz gets photographed with two young girls. Blonde women doing field work are not that common here.

last time I was here, two years ago.

We brought along lots of extra equipment in case anything had broken down. Humayun and I worked on downloading the GPS data while Liz and the guide went for a walk and climbed the observation tower. They got to see deer, wild boar and a monitor lizard, while Humayun and I sat in a dark room. As usual, we struggled to remember how to connect and download data exacerbated my unfamiliarity with the Windows OS on the PC we were using.

The M.B. Mowali, our home for the next two days for the run to Hiron Point and back.

The M.B. Mowali, our home for the next two days for the run to Hiron Point and back.

Eventually, we got it right and were happy to see that the system was working perfectly, data files for every day since I last visited. Obviously, because we had brought all the equipment along, we didn’t need it. We downloaded all the data and then changed the SIM card in the modem. We had set up cellular communications when we installed the station, but the signal was too weak to every collect any data. Now there is a good signal here from a different cell phone company. When we get back we will have UNAVCO check to see if it works. In any case, we now have enough data to measure the subsidence here.  The sinking of the land exacerbates the impact of rising sea level. Only the vast sediment supply of the delta counters it to maintain the land. And that is at risk from human intervention.

Humayun having tea in the morning on the Mowali.

Humayun having tea in the morning on the Mowali.

We had tea and cookies with the forest ranger and then headed back before low tide trapped us in the channel. As things went well, we stopped on the newly emerged char land and Liz and I walked around examining the sediments, surprisingly sandy for a tidal estuary. Back in the speed boat, we crossed the broad channel and then paused to watch the sunset on the water. Once on the Mowali, we sailed to where we would spend the night in the Mangrove Forest and now I got to see deer and boar on

Sundarban Mangrove Forest at low tide.

Sundarban Mangrove Forest at low tide.

the way before darkness descended. There was even a herd of 9 or 10 just across from where we rejoined the Mowali.

In the morning, we started heading north. Because it was very foggy, we stayed in smaller channels for a few hours before entering the main channel of the Pussur River. I spent the early morning before breakfast watching the forest go by and spotted a few more

One of the many chital, or spotted deer, we saw along the way.

One of the many chital, or spotted deer, we saw along the way.

deer. By noon we were out of the Sundarbans and ready to drop off our guard. I actually hadn’t seen him for the entire trip. We continued past the Rampal power plant. This a coal-fired plant being built less than 20 km from the Sundarbans. Most of the coal for it will likely be transported up the Pussur River through the Sundarbans. It is the subject of a lot of protests, including the hartal we had last week, but they are not likely to stop it from being built. A short time later we met up with the Bawali and

Getting into the speedboat to sail across the channel to Hiron Point.

moved back across. Then, work here being done, both ships sailed up to Khulna for the night. Tomorrow morning we disembark for the next phase of the trip.

Having tea with the forest ranger after completing our work.

Al fresco dinner on the Mowali.

Sunset over the Sundarbans and one of the many ships plying the waterway.

Equipment repairs in SW Bangladesh

Tue, 01/31/2017 - 04:53
Having a breakfast of an omelet and paratha while waiting at the ferry ghat (dock) at Mawa.

Having a breakfast of an omelet and paratha while waiting at the ferry ghat (dock) at Mawa.

After a night in Dhaka, our group temporarily split up. Chris and Dan headed to Khulna in the SW at 4 am to avoid the hartal (general strike) that was planned for 6am-2pm. Liz and I stayed in Dhaka for a day. I spent it mostly editing material for a new project. The next day Liz, Humayun, my partner from Dhaka University, and I followed the others to Khulna, crossing the Padma (combined Ganges and Brahmaputra) River by ferry at Mawa. After waiting an hour, Humayun used a connection from a former student to get us on the next

Mofizur removing the antenna and antenna mount from the listing GPS pillar while I watch from the side.

Mofizur removing the antenna and antenna mount from the listing GPS pillar while I watch from the side.

ferry, a fast one. It is impressive how much the river has silted up since the last time I crossed here. Another few hours and we arrived at our compaction meter site SE of Khulna. We picked up one of the 4 sons from the family that takes care of the site. Mofizur, the second son, now a student at Chittagong University, is returning home for the first time in 6 months. Making the weekly measurements has been passed along from the oldest to youngest sons. It made for a great welcoming by the Islam family when we arrived mid-afternoon.

Me sighting through the optical level to get the relative elevations of the 6 optical fiber compaction wells.

Me sighting through the optical level to get the relative elevations of the 6 optical fiber compaction wells.

The last time I was here, the river adjacent to the site was being dredge and widened. It had gone from 200 m wide to just a few and was now too small for boats except at high tide. The widening cut into the bank that held our instruments. While the engineer tried to leave us enough room, it clearly didn’t work. The pillar that holds the GPS antenna is tilting badly towards the stream. They have secured it with ropes to keep it from completely falling over. We got hold of a ladder and removed the unusable antenna. Mofizur climbed up, afraid that I weighed too much for the fragile system. Next, Humayun and I surveyed the monuments for the compaction meter wells. We had to dig out the sediments

Liz measures and describing the sediments that have accumulated over the base of the wells since they were installed in 2011.

Liz measuring and describing the sediments that have accumulated over the base of the wells since they were installed in 2011.

covering the base. Liz measured the thicknesses, which were 4-7 inches. We could clearly see the finely layered sediments deposited from before the river was enlarged to the thick muds that accumulated afterwards. The sedimentation rate had clearly increased due to the river widening. The survey will give us the relative heights of the wells. When we get back we will compare it to earlier measurement to see if the wells have shifted, too. Without the GPS we cannot determine the absolute elevations. Our last task was to measure the lengths of the optical fibers in the wells. We brought along a new laptop to work with the electronic distance meter (EDM), but we found the recharger was still in Dhaka. We had forgotten it. With a dead battery and no way to recharge it, the measurements will have to wait until Humayun can send the recharger.

LunchKHLC

Mr. Islam serves some fish to Humayun, Liz (taking photo) and myself in their courtyard as part of the feast that they prepared for us.

While we were there, we were served lunch, a huge banquet. Three finds of fish, chicken, rice, vegetables, two desserts. The three of us sat a table outside in the yard, while the family plied us with the delicious home-cooked Bangladeshi food. The more important the guests, the more food and were were suitably overwhelmed. And since it was after 3 pm, we were famished and did our best make a dent in it. Since the GPS is no longer usable, we left them the battery and solar panel that was powering it, doubling their electricity supply. Before we installed the

The M.B. Bawali, our home for the next five nights and four days. Everything is great except for the cold water showers.

The M.B. Bawali, our home for the next five nights and four days. Everything is great except for the cold water showers.

equipment in 2011, they did not have electricity at all. After some heartfelt farewells, we headed to Khulna to meet up with Chris, Dan and Matt Winters, my TA from the class I taught in 2015. Fluent in Bangla, he has been working with Chris on field observations for his Master’s thesis at Columbia. He and some of his assistants will join us for a few days. The three of them had a dinner meeting, so my group headed to the M.B. Bawali, our home for the next 4 days. Smaller than the M.B. Kokilmoni, it is a perfect size for our group.

Humayun inspecting our equipment on the roof of a school on Polder 32. The tower is a meteorological station and our GPS antenna is on the back wall.

Humayun inspecting our equipment on the roof of a school on Polder 32. The tower is a meteorological station and our GPS antenna is on the back wall.

The next morning, we headed for Polder 32, the embanked island we have been studying. Humayun and I will visit the GPS station we set up there in 2012. It has a cellular modem so data can be downloaded remotely every day, but stopped working in November. It seemed that the receiver was not recording satellites, so we brought along replacement antennas, cables and lightning protectors. Another GPS station had a similar problem and there the cable had to be replaced. When we arrived at the school, we found the receiver was tracking satellites. We didn’t

Humayun stripping the end off the coaxial cable that we used as a grounding wire.

Humayun stripping the end off the coaxial cable that we used as a grounding wire.

have to track down a break in the system. But why wasn’t it recording data. The best we could ascertain was the modem had hung up; rebooting it fixed the problem. It was working, but I don’t understand what happened enough to be sure it won’t happen again. Hopefully, now that it is working, the engineers at UNAVCO can log in an work on it. When we doublechecked everything, we found that the grounding wire was missing. This is unsafe. If there is a lightning strike, the lightning protector blows the connection

A stopped to pay our respects to the small shrine in the schoolyard to Saraswati, the Hindu goddess of knowledge and education.

A stopped to pay our respects to the small shrine in the schoolyard to Saraswati, the Hindu goddess of knowledge and education.

to the equipment inside and shunts the electricity down the grounding wire. We cannot put a school full of children at risk. The only wires we had were the coaxial antenna cables. We stripped the ends off a partial cable and wired it between the cut ends on the roof and near the ground. We made a visit to the Hindu goddess of education and headed back to the ship having done all the repairs we could, and satisfied that the school was safe.

Heading back to the Bawali on the country boat after a successful day on the Polder (embanked island).

Heading back to the Bawali on the country boat after a successful day on the Polder (embanked island).

Back to Bangladesh to date earthquakes and more

Fri, 01/27/2017 - 01:06

 

 

 

 

 

 

GroupWPolice

Our group, Dan, Liz, Chris and myself, posing with our police escort at the Amtali Resort

TreesFog

Trees peaking out from the fog in the early morning on the Rashidpur anticline. The anticlines are covered by forests and tea gardens (plantations)

It has been over a year since I was in Bangladesh after coming here twice a year for the previous five years. This will be a packed trip doing many different things, collecting samples, fixing equipment, visiting rivers and hopefully meeting with the public and government officials about the earthquake hazard. My paper last year showed that there is the potential for an earthquake of at least Mw8.2 here, an area with ~140,000,000 people. However, with no knowledge of when the last megaquake was or how often that comes, we don’t know when it might occur, in years or centuries. The article received widespread coverage in the press and caused a panic in the region. Now I feel an obligation to help steer things towards better preparation and building construction.
Our first task is related to a past earthquake. The last time we were here, Céline and I collected samples from an abandoned river that shifted ~20 km to the west. We think the shift was caused by an earthquake, but we don’t know if it

View of the banks of the Kushiara River in NE Bangladesh where we are looking to sample

View of the banks of the Kushiara River in NE Bangladesh where we are looking to sample

was a moderate M7 or a large M8.5. Either one could be pretty destructive to people living on the soft delta sediments. We now have dates for the samples. The 3 ages we got for the last sediments deposited before the shift, or avulsion, were 3800, 3800 and 3600 years ago. The method we used was OSL, optically stimulated luminescence, dating. It measures electrons trapped in quartz crystals. The electrons are so weakly trapped, that sunlight can set them free. Thus we date how long it has been since the sediment has seen the sun. The one

Chris on the boat taking a photo with the highway bridge over the Kushiara River in the background

Chris on the boat taking a photo with the highway bridge over the Kushiara River in the background

hitch is the possibility that when the sediment was transported down the river, not all the electrons were freed. This is known as incomplete bleaching and would result in too old an age. Our solution is to collect samples from the modern river to see if there is any residual age that would shift our estimate for the earthquake.
Four of us arrived together, Chris Small and Dan Sousa, who use remote sensing to study the changes in the delta: rivers, coastline, vegetation, Liz Chamberlain, a graduate student specializing in OSL and

A group of girls excited by the strange visitors to their village asked me to take their picture.

A group of girls excited by the strange visitors to their village asked me to take their picture.

myself. On arrival, we were met by Saddam Hossain and headed NE towards the Kushiara and Meghna Rivers. We stayed the first night in a “resort” in the folded hills of Sylhet where tea is grown. As a result of the attack on the Holey Artisan Bakery last year, the country is taking precautions. When we entered the Sylhet Division, we were met with a police escort. They stayed with us all through the nigh and their relief through the next day until we left the Division on our way to Dhaka. This is a new experience for me. It did have the

A set of colorful houses line the bank of the broad Meghna River. We continue south to find sampling sites.

A set of colorful houses line the bank of the broad Meghna River. We continue south to find sampling sites.

advantage of being able to drive without stopping for tolls and the police used their siren to help with passing cars. Still we only got to our room around midnight, a long drive after two long flights.
Our first stop was the Kushiara River, a bit upstream of the river avulsion, but above the lake that forms every summer during the monsoon. My concern is that the lake decants the sands so the sediments upstream and downstream of the lake are different. Thus we will sample both. We drove to the small town

Chris, Dan and Liz on the country boat scanning for good sampling sites.

Chris, Dan and Liz on the country boat scanning for good sampling sites.

of Sherpur and the police facilitated renting a small boat. Sailing along the river, we spotted a good spot where the bank was eroding and we could easily collect samples. This was as simple as cleaning a spot and then hammering an iron tube into the deposits. The main precaution is that the sample must not be exposed to light or it will lose all its electrons. We then decided to collect a sample from the river bottom from the boat. This proved more challenging and it took several tries to get the boat into the

I am hammering our iron pipe into the eroding cut bank to collect a sample without exposing the center of it to light so it can be use for OSL dating.

I am hammering our iron pipe into the eroding cut bank to collect a sample without exposing the center of it to light so it can be use for OSL dating.

correct depth of water and collect a sample with the sampler at the end of a several meter long augur. We found we had to work fast as the boat would drift in the strong current. By noon, we had our two samples and headed to the Meghna River on the way back towards Dhaka.
The much larger and more industrialized Meghna River was a bit more challenging. We need an area undisturbed by people. We rented a country boat at the ghat (dock) near the Bhairab Bazaar Bridge over the river and sailed off. After almost an hour on the river, we found it. The nose of a large island and an eroding cut bank nearby. The point of the island was protected by sand bars, so Liz and I got out and sampled the bottom with the augur. Not movement to worry about when the boat is aground. Then we headed to the cut back exposure and took our 4th and final sample. The set of samples is different then I envisioned, but with Liz’s guidance, they will fit the bill well. By the time we got back to the ghat it was dusk. Time for a slow and traffic filled drive to Dhaka. We got in just in time to rush off to our favorite restaurant for a celebratory dinner at our favorite restaurant before it closed. This trip is off to a great start.

The Coming Great Quakes in India and Bangladesh?

Tue, 10/18/2016 - 11:54

A new film takes viewers from the eastern highlands of India to the booming lowland metropolis of Dhaka, the capital of Bangladesh–and explores an ever-more detailed picture of catastrophic earthquake threat that scientists are discovering under the region.

Scientists from Columbia University’s Lamont-Doherty Earth Observatory, the University of Dhaka and other institutions have been working for more than a decade to understand deeply buried geologic structures that could produce earthquakes here, one of the most densely populated places on earth.  No one can predict when the next quake will strike, or how big it will be–but clearly there is potential for a very large one. “Some of this have long suspected this hazard, but we didn’t have the data and a model,” says Lamont-Doherty geophysicist Michael Steckler, leader of a recently published study outlining the threat.

Under Bangladesh, India and neighboring Myanmar, the scientists have found signs of a megathrust–the meeting of two gigantic moving tectonic plates, with one diving under the other. But the plates don’t seem to be moving right now; they are locked, and strain is building. The researchers say that when–not if–the plates do slip, destruction and casualties could be massive. Some 140 million people might be affected.

The hazard has been hard to assess up to now, because most of the region’s underlying geology is covered by the world’s largest river delta–miles-deep layers of sediment carried down from the Himalayas and built up over millennia. The team has deployed seismometers, GPS instruments, satellite imagery and other technology to draw up a picture of what is going on down below.

The region is unprepared. Not only are many people too poor to build earthquake-resistant structures. “From history, there’s been a lot of destructive earthquakes in this area, but there hasn’t been one in recent years, so people tend to forget,” said Lamont-Doherty geologist Leonardo Seeber. Geologist Humayun Akhter of the University of Dhaka, said, “Our cities are not built in a planned way, and this cannot be changed in a few years. So we have to work within this system, and teach our people how to cope.”

The movie was made by filmmakers Douglas Prose and Diane LaMacchia with support from the U.S. National Science Foundation. The NSF also funded the research.

 

Construction in the Swamp

Tue, 08/16/2016 - 22:48
Cap'n Mark's mudboat loaded with planking for the walkway.

Cap’n Mark’s mudboat loaded with planking for the walkway.

The weather is miserable, but there is no let up in the forecast. However, we seem to be in a local area of less rain, and more importantly no lightning. The worst weather is in northern Louisiana. They are getting 15-20”. While waiting for a break in the weather, we assembled some of the wooden planks into walkway sections. As the rain let up a little, we finally decided to go for it and head to the site. We loaded up the mudboat and Don and Keith took a load over to lay down the walkway. Don is the technician

Carrying the lumber down the plank walkway

Carrying the lumber down the plank walkway in my borrowed duck hunting suit.

for the fiber optic system and Keith is a UNAVCO GPS engineer. Tim is a professor specializing in geodetics, while I have experience with subsidence on a variety of scales, including our GPS and compaction meters in Bangladesh. When they returned, we followed with more of the supplies. The wooden walkway allowed us to only sink up to our ankles instead of our knees in the mud. Carrying the supplies out, we started construction

Keith holding the post while Don gets ready to use the pressurized water jet to help insert it into the ground.

Keith holding the post while Don gets ready to use the pressurized water jet to help insert it into the ground.

on the structure that will hold most of the equipment – solar panels, GPS receivers, batteries, modem. Sinking the six 4×4 columns into the mud was tough, but less so than we envisioned. After that, we managed to get most of the structure built while Don worked on the compaction meters. We were completely soaked, but got a satisfying amount done. Returning to camp, we spent the rest of the day planning, buying more supplies, and dinner. Our biggest question mark is how to attach a GPS antenna to the reference rod that goes

Keith and Tim screwing the framing onto the structure after sinking the posts.

Keith and Tim screwing the framing onto the structure after sinking the posts.

down 37 meters to the bottom of hole 1. The size of the rod and the standard thread size for GPS equipment do not match. Adapters are not readily available. Tim and I wanted to install GPS antennas on both the reference rod and the upper casing, but it is not clear whether the two antennas will interfere. We decided against putting two on the same well, but may add it later if feasible.

The next day, the weather remains lousy, but we are still in a pocket of less rainfall

Keith and I pose by our newly installed solar panels . These will power both the GPS and the optical fiber strainmeters.

Keith and I pose by our newly installed solar panels . These will power both the GPS and the optical fiber strainmeters.

than much of Louisiana. We started out soon after sunrise. All the rain meant that the planks sank farther into the loose mud than the day before. By now, walking in thigh high muddy water all the time is usual. We split into different tasks. Tim and I mounted the solar panels, Keith set up the GPS antenna mounts and Don redid the compaction meter electronics. Later Keith and I set up the receivers and batteries while Tim and Don redid the conduit connecting the compaction meters to our control platform. Tor Tornqvist and a John, a

The waterproof box that holds the 3 GPS receivers and other electronics. I protected it with an umbrella during the installation - until the wind destroyed it.

The waterproof box that holds the 3 GPS receivers and other electronics. I protected it with an umbrella during the installation – until the wind destroyed it.

graduate student from Tulane University, visited us in the morning and went back to the camp via a pirogue, a small Cajun boat. As time went on, the rain lessened. Best weather we’ve had. We are working well together. Hardship makes for good bonding. By 2pm, we had finished all we could do today and called for Mark to take us back.

We decided we needed a machine shop to make the adapter, which needs to be stainless steel. That is not possible until Monday morning. The rest of our needs we could get at a hardware store. After

Tor and John paddle away from the site in a pirogue

Tor and John paddle away from the site in a pirogue.  It will be a 20-minute trip back to the camp for them, with a tailwind.

lots of discussion about the plans, Tim delayed his flight home. Don will decide at 10 am tomorrow morning if he needs to delay his flight. The aim is for everything but the reference rod to be done by midday tomorrow. If so, Don can leave. Keith will stay to the end, to set up he reference rod. Since so little is left that needs manpower, now that the major construction is done, I will leave as scheduled tomorrow morning. We are approaching completion of the site. While I hate leaving before it is completed, I have other commitments and this group can easily do the work without me. We will shortly have two extremely sensitive compaction meters and three GPS receivers to monitor ground subsidence and sediment compaction. If we can get more funding we will install another optical fiber in the middle depth hole and another GPS. Meanwhile we have the world’s best compaction meter in one of the world’s worst sites for fieldwork and solid ground.

P.S. Don delayed his flight and Sunday and Monday the group finished everything. A machine shop built the missing parts on Monday and Keith, as the only one remaining, will install it Tuesday. Success, despite the weather.

Visit to a Different Delta: the Mississippi

Tue, 08/16/2016 - 00:00

 

Structure at Well 1, the deepest one, with the temporary solar panel and electronics.

Structure at Well 1, the deepest one, with the temporary solar panel and electronics. The Mississippi River is behind the line of trees in the background.

This summer I am visiting a different delta. I am in the Mississippi Delta in Louisiana rather than the Ganges-Brahmaputa Delta in Bangladesh. We are installing several GPS as part of a system of instruments to measure sediment compaction. In Bangladesh, we have installed two sets of wells drilled from 20-300 meters deep with stretched optical fiber strainmeters. We measure the length of the fiber every week and have been watching as they shorten when the sediments compact. Now, a group of us has been able to get

Tim and Keith examining Well 3, the shallowest well.

Tim and Keith examining Well 3, the shallowest well.

funding to put an improved system in the Mississippi Delta near where land subsidence and deposition is already being measured.The effort started a few years ago at a meeting on coastal subsidence in New Orleans, which worsens the problems of sea level rise. A group of us combined to propose a “supersite” where we could apply multiple methods to measure subsidence and compaction. Mean Allison and Tor Tornqvist were finally able

Don sits on well 1 to see how much motion the compaction meter will pick up.

Don sits on well 1 to see how much motion the compaction meter will pick up.

to raise enough money from the Army Core of Engineers to drill 3 wells and install new generation optical fiber strainmeters in them. These provide continuous measurements accurate to better than a millionth of a meter. The wells were drilled in January and are 37, 90 and 128 feet deep. Mark Zumberge’s team installed strainmeters in the shallowest and deepest wells in July. Now I am here in Myrtle Grove, Louisiana with Tim Dixon, Don Elliott and Keith Williams to install 3 GPS receivers at the site, two

Here is how I looked during the rain on the first day.

Here is how I looked during the rain on the first day.

attached to the casing and the tops of wells and on a rod that goes all the way to the bottom of the deepest well. These will give us the absolute elevations of the tops and, in one case, the bottom of the wells. We will also build a new platform to host the receivers, batteries, solar panels, and all the electronics, including the modem to transmit the data. Then all the gear will be separate from the wells.

After arriving and meeting up over dinner, we drove to the “camp”, house we are renting at the Myrtle Grove Marina near the site. It is usually used as a vacation home and for duck hunting. The site itself is only accessible by boat. It is only a 10 minute ride by mud boat, a flat bottomed skill that

Tim emptying the muddy water from his boot.

Tim emptying the muddy water from his boot.

can travel over almost no water. An air conditioning breakdown upstairs left us all sleeping downstairs on the couches and the floor. More importantly, the weather has been rain and thunderstorms for days. In the morning it was still raining pretty hard, but no lightning. After a lot of discussion on possible ways to do the installation, we were able to take advantage of a break, or at least lessening of the weather, to visit the site. Mark Brockhoeft took us out on a mudboat into the marsh. After working there with rain from above and mud and water below, we sailed back with a plan of how to proceed. Mark leant me better gear for working in the rain and mud, which were much worse than I expected. Later in the day, Don and Keith got the supplies we need and we started preparing to head out tomorrow to start construction, weather permitting.

Last Sample and Home

Tue, 10/20/2015 - 16:42
Digging the mud pit for the tube well at the side of the elevated highway.

Digging the mud pit for the tube well at the side of the elevated highway.

We finished our work at the river transect. Now we had one more sample to collect. It was to the north where the abandoned valley is still flooded at the site of the tube well that started this idea. It is well BNGB013 along one of the transects that was done for the BanglaPIRE project. It was done along the side of a major “highway”, so will be accessible and it not far out of our way home. Alamgir had a contact in a nearby village and arranged, and rearranged a driller. We were glad to be heading back

View across the river valley from the road.  The broad valley is mostly still underwater over a month after the end of the monsoon.  The road I am standing on is elevated so it does not flood, while the drillers work from the base of the road.

View across the river valley from the road. The broad valley is mostly still underwater over a month after the end of the monsoon. The road I am standing on is elevated so it does not flood, while the drillers work from the base of the road.

to Dhaka. The hotel we stayed in was the best in Brahmanbaria, but it had bedbugs. In this moderate sized town, the choice of restaurants was limited.

The drillers arrived at our meeting place late. There was a fight between two villages the night before and some people were stabbed. They own a plot of land along the main road in the other village. Those villagers wanted them to swap it for land perpendicular to the road, but they refused. The land along the road is valuable for shops. The result was a fight until the police broke it up, but several people ended up injured. They came without their equipment so

Drilling our last tube well.  It is at the site of one we drilled a few years ago.  Knowing the stratigraphy, we can drill directly to the sampling depth.

Drilling our last tube well. It is at the site of one we drilled a few years ago. Knowing the stratigraphy, we can drill directly to the sampling depth.

they could sneak quickly through the other town. They got what they needed at the store where we met about 2 km west of the well site. I went ahead and located the exact place we wanted to sample.

Since the well had already been logged and sampled, we only needed to drill down to the sands, making sure the stratigraphy agreed. Relooking at the logs of the well, I realized that we barely had enough extension rods to make it to the sampling depth. Luckily we hit the sands with a couple of feet to spare. We

Matt and Céline examine the PVC tube that will hold the sample shortly.

Matt and Céline examine the PVC tube that will hold the sample shortly.

got our sample and headed for Dhaka. Of course, we hit terrible traffic and were late to dinner with other scientists from our project that just arrived from the U.S. Over dinner I learned that Kazi Matin Ahmed, one of the Dhaka University professors we work with was from a town right near our sampling. He said that growing up he would go to school by boat during the monsoon. The next day was packing up at the university and making copies of everything. We also had to pack up a number of GPS and seismic recorders that need to be returned to the U.S. for repairs. Unsalvageable was one from Madhupur that was destroyed in a fire. This trip was very successful; we achieved all our goals, although as usual, there were a lot of changes of plans on the fly. In Bangladesh, nothing goes as planned, but we always get everything

The drillers insert the larger diameter 4" PVC pipe into the well.  Handling the 10 meter pipe is challenging.

The drillers insert the larger diameter 4″ PVC pipe into the well. Handling the 10 meter pipe is challenging.

done. Bangladesh is a country of resilient people who know how to get things done.

A group photo taken at our lunch stop.  In front are Chapin and Farouk, our drivers, myself, Basu and Céline.  In back are Matt, Alamgir and Atik.

A group photo taken at our lunch stop. In front are Chapin and Farouk, our drivers, myself, Basu and Céline. In back are Matt, Alamgir and Atik.

OSL Samples at Last

Tue, 10/20/2015 - 15:02

 

Basu and Céline describing the sediment samples from  a tube well.

Basu and Céline describing the sediment samples from a tube well.

We planned to drill four or five tube wells across the abandoned channel and pick one for OSL dating samples. With the success of yesterday’s tube well drilling, we were optimistic that we could actually do the sampling. We met the drillers in the morning and headed to the next site. Since only two or three people are needed for logging the well, we left Céline and Basu and the rest of us headed off to do a short resistivity line near the first drill site. We scouted it during the drilling of the first well. On the way to the resistivity

Eating a picnic lunch in the field at side of the road.  Vans on either side protected us.  We usually had bananas, oranges, crackers, cakes and on this day pineapple as well.

Eating a picnic lunch in the field at side of the road. Vans on either side protected us. We usually had bananas, oranges, crackers, cakes and on this day pineapple as well.

site, we selected locations for three more wells. Depending on time, we will either drill two and then the sampling well or just three stratigraphic wells. Since it will be only 2 meter spacing between the electrodes, it will be quicker to set up despite less people. We are only trying to image the channel, so we don’t need a larger spacing. The site was also drier than the first two resistivity lines. We laid it out and started collecting data. My only concern was that the route was used as a path for local farmers collecting hay. I didn’t want them to knock off the electrode connections or to have them

A strong rainstorm slowed the work, but couldn't stop it.  Here our driller take a short, wet break.

A strong rainstorm slowed the work, but couldn’t stop it. Here our driller takes a short, wet break.

shocked by the pulses of electricity we sent through the electrodes.

Once the line was running, I headed back to the drill site. They once again found a think mud layer over sand. They continued drilling deeper and found the silt clay that marks the boundary between the Holocene and Pleistocene, when sea level rose following the end of the last ice age. This was a bonus and confirmed that we were on line with the Lalmai anticline farther south. We shifted to the next line, a more difficult location next to a pond, but they managed. I headed back to the resistivity line and found them starting to pack up the equipment. When I went to take a look at the instrument, I found it hadn’t finished. It had run out of memory for recording line and stopped. We quickly reinstalled the electrodes that had been

Attaching the larger 3.5" drill bit to the end of the pipe to enlarge the initial hole so we could sample through it.

Attaching the larger 3.5″ drill bit to the end of the pipe to enlarge the initial hole so we could sample through it.

pulled that we still needed. I deleted some older files that had already been downloaded and restarted acquisition. We had only lost four of 584 command lines.

By the time the second well and the resistivity line were done, it was questionable as to whether we could do the sampling well, which will take longer. The drillers going off for a lunch break settled it. We would do a third tube well today. During the drilling, the skies that had been threatening all day opened up.

Cutting the 3" PVC well liner to keep the hole open until we could sample.  We assembled two different lengths for the samples above and below the mud-sand transition.

Cutting the 3″ PVC well liner to keep the hole open until we could sample. We assembled two different lengths for the samples above and below the mud-sand transition.

The drillers and loggers got completely soaked, but kept going and we completed our five-well transect of the river valley. In the evening we compiled all the logs and discussed a sampling plan. Rather than take four samples in one well, we decided to take two, one above and one below the sand-mud transition in two different wells.

The OSL sample is over 2” wide and the wells we drilled were 1.5” wide. The driller decided it was best to drill a 1.5” well to the depth of the first sample, a few feet above the transition, and then overcore it to 3.5”. Then 3” wide PVC pipe

Hammering the OSL sampler, which is at the end of many auger extension rods.  The sampler fits inside the 3" PVC pipe that had been installed.

Hammering the OSL sampler, which is at the end of many auger extension rods. The sampler fits inside the 3″ PVC pipe that had been installed.

was lowered to keep the well from collapsing. Finally, we put the sampler on the auger rods and lowered it to the bottom of the well. We, actually people younger and stronger than me, pounded the sampler 30 cm into the bottom. Then we all had to pull up on it to get it out. The next step was to extrude the sample in its liner into a thick PVC pipe casing. The sample must be kept in the dark, so this was done inside a black plastic bag. Then the entire sample is wrapped in the black plastic bag and taped securely. The ends and outside of the sample will be discarded and only the core of the sample will be used for dating. Later, sample preparation will all have to be done in a darkroom. I helped sample on my last trip, but the was the first time I was in charge of the procedure. It went well. After the first sample, the drillers drilled to 1 ft. past the contact, overcored to the same depth, added the PVC liner and we sampled again. We

Matt, Céline and myself in a lungi toast the successful OSL sampling with green cocoanut water.

Matt, Céline and myself in a lungi toast the successful OSL sampling with green coconut water.

repeated everything for the second well and we had four OSL samples. We celebrated with green coconuts.

Tubewells to the Rescue

Sat, 10/17/2015 - 10:37
One of our cars drives over the makeshift road repair of a sandbag, bricks, wood and rebar while the entire village looks on.

One of our cars drives over the makeshift road repair of a sandbag, bricks, wood and rebar while the entire village looks on.

The next day we went out again for resistivity and augering. Céline picked out two alternative sites that might be drier. We drove through the abandoned valley to the site. We took the direct route and found the local road to be in a terrible state of disrepair. The vans could barely make it through. Then we hit a spot where slumping off each side of the road narrowed it too much. The villagers helped make a temporary road with bricks and wood, but it was still too narrow. Then they filled a sandbag and together with the bricks, wood and other

Céline watches the repair with some of the village women

Céline watches the repair with some of the village women.

handy items we got across. It turned out that since the Upazila (county) voted for the opposition party, they have not had their roads repaired for over a decade. This level of politicization of everything in Bangladesh really hurts the country. When we reached the location of the line, we found that ponds between the road and the fields limited our access. We walked around and found a site next to a brick factory. The line was along an irrigation ditch. Fine to walk on either side, but submerged to mid-shin if you

Standing ankle deep in mud by the resistivity meter.  The smokestack of the brick factory can be seen in the distance.

Standing ankle deep in mud by the resistivity meter. The smokestack of the brick factory can be seen in the distance.

stepped in the middle. The data looked very good after processing. We may have found the top of the Pleistocene as relatively shallow depths consistent with the site being the top of a buried anticline (folded hill).

The delays from the bad road, site searching, and a longer distance to lug the equipment meant that we couldn’t do augering. We came to the conclusion that we have to alternate days of resistivity and drilling. Not enough time in a day to do both properly. That meant

Céline and Basu describe the core brought up in the half-circle auger gouge.

Céline and Basu describe the core brought up in the half-circle auger gouge.

the next day was for augering. We went back to the soccer field site, officially BNGTi1, and started augering with all six of us. We hurried past the section we had already described. To minimize hole collapse, we switched between two augers and tried to work quickly on the descriptions. It took all of us all morning to make it to 4.8 meters. The mud was too hard. We needed to go to plan B. We would drill tube wells and sample inside the wells. Alamgir and Basu went off to the village to find a driller. The rest of us

The three-person drill team preparing the site.  Digging a post hole with rebar, inserting the bamboo pole and digging the mud pit with a kudali.

The three-person drill team preparing the site. Digging a post hole with rebar, inserting the bamboo pole and digging the mud pit with a kudali.

cleaned off the equipment and ourselves at a nearby pond and well and had lunch. After several attempts, they found a driller, but he couldn’t come until 3 p.m. I like to use all the available time I have here, but we now had a few hours break.

The three-person drill team arrived right at 3, unusual in this part of the world. I have seen the drilling technique before, but never the initial set up. In 20 minutes they set two vertical bamboo poles in the ground, tied on the cross piece to make a large H, attached a lever arm and the drill pipe, dug a mud pit for water and a

The driller standing on the frame uses his palm to keep a seal on the pipe as the lever is used to lift and drop the drill pipe.  On the fall, the mud come squirting out of the pipe.

The driller standing on the frame uses his palm to keep a seal on the pipe as the lever is used to lift and drop the drill pipe. On the fall, the mud come squirting out of the pipe.

channel to the actual well location. Then they started drilling. It was so much faster and easier than augering! In 10-20 minutes they were past the depth we reached. We don’t get continuous samples described every 10 cm (4 in.), but the lithology averaged every 5 ft. Muds come up as solid cylinders that we collect, sands as a slurry that we decant. We subdivide the 5 ft. sections if there is a lithology change. The driller caught on quickly to what we wanted and kept us informed of all changes in sediment type, which he could easily feel. Céline and Basu, an experienced logger of tube wells, did most of the sediment work,

As the drilling proceeds, the top of the pipe drops to ground level and then a new pipe is added to continue the drilling

As the drilling proceeds, the top of the pipe drops to ground level and then a new pipe is added to continue the drilling

with some help from the rest of us. As expected, the section was primarily mud with some silt. We reached the sands from the abandoned channel at 42 ft., a little deeper than I expected but reasonable. It was still early enough for us to do another. Alamgir and I scouted a second location as they finished and packed up the equipment. We completed that one, with the sands at only 20 ft. North of our transect looks like there was an island splitting the channel in two. Here would have been downstream of the island, so we

Céline and Matt walk back after a satisfying day.

Céline and Matt walk back after a satisfying day.

expected it to be shallow. Finally, things were going well. Using tubewells, we should have plenty of time to drill several stratigraphic wells and then pick one for sampling. We celebrated with dinner at the local Chinese restaurant.

Pani, Pani Everywhere

Wed, 10/14/2015 - 07:46

 

House in the middle of the wet fields. During the summer monsoon, it will be an island connected by the bamboo bridge.  In a month it will be connected by dry land

House in the middle of the wet fields. During the summer monsoon, it will be an island connected by the bamboo bridge. In a month it will be connected by dry land.

Six of us headed out on Oct. 8 for Brahmanbaria, northeast of Dhaka. Our target is a large winding abandoned river valley that we believe used to be the course of the Meghna River. Currently, the much smaller Titas River flows northward in the channel. Why would a river in the world’s largest delta flow the wrong way? We think that an earthquake uplifted the Comilla District area to the south. That caused the Meghna River to shift westward to its present channel and the Titas to flow up the old channel. A well drilled in the channel in 2012 shows a layer of muds overlying coarser sands.

The large abandoned channel we hoped to work in is completely flooded.

The large abandoned channel we hoped to work in is completely flooded.

We think the sands represent sediments from the old Meghna and the muds are sediments filling up the channel. We will be using resistivity to image the channel and an auger to first sample and describe the sediments and then to collect samples for dating.

Finding organic matter to date by carbon 14 is rare, so we plan to use a technique called OSL dating. OSL stands for Optically Stimulated Luminescence. Electrons from the radioactivity of all rocks get trapped in defects in quartz grains. However, they

A group of children play in a pond while we try to figure out where to find land dry enough to work in.

A group of children play in a pond while we try to figure out where to find land dry enough to work in.

are so weakly trapped that sunlight can release them. When traveling down the river, the electrons are released and then start accumulating when they are buried. By measuring the light released by the sample when optically stimulated, we can calculate the time since the sample last was exposed to light. By sampling the top of the sands and the bottom of the muds, we can date the time the river switches, or avulsed. The details of the procedure to get an OSL age are pretty complicated, but if this works, we

Our resistivity meter set up in a rice field.  We were able to collect data at the cost of very muddy legs.

Our resistivity meter set up in a rice field. We were able to collect data at the cost of very muddy legs.

will date the earthquake that caused the river avulsion.

This technique is new to me. I helped with some sampling the last time I was here, but I have not been in charge of doing it. I am also more comfortable with the quantitative data from the resistivity than the qualitative geologic descriptions we will make of the sediments. Luckily I have a good team with me, Céline, my postdoc, Matt, my former teaching assistant, and Alamgir, Atik and Basu from Dhaka University. I have spent time in the field with Alamgir and

Spools of the cable we use along where we collected the profile.  We used the slightly raised boundaries between fields for access, to avoid stepping on the crop and to stay a little less muddy.

Spools of the cable we use along where we collected the profile. We used the slightly raised boundaries between fields for access, to avoid stepping on the crop and to stay a little less muddy.

Atik before. Alamgir has conducted his own resistivity surveys. Basu was recommended to me as someone with a lot of experience in describing sediments.

We set out early in the morning for the four-hour drive. However, when we reached the river valley, we found it was almost completely flooded. We walked out on an elevated road and there was pani—the Bangla word for water—everywhere. The abandoned valley is still slightly lower in elevation than the surrounding land. Even that land has the rice fields flooded with shallow water, although the

Céline and Basu examine a core of samples brought up by the auger gouge.

Céline and Basu examine a core of samples brought up by the auger gouge.

boundaries between the fields are above water. But our main target is submerged! In the winter this will be dry land, but we are a month and a half too early. A number of scheduling issues required me to come now, although I knew it was too soon after the monsoon, but I didn’t expect so much of the land to still be flooded. Time to come up with an alternative plan.

For the resistivity, we need long straight stretches of dry land. We decided to

Kids playing soccer on the open field where we did our first auger hole.  The auger was hit by the ball several times.

Kids playing soccer on the open field where we did our first auger hole. The auger was hit by the ball several times.

do it west of the valley to try to image the thickness of the entire Holocene (last 10,000 years) section. It should vary because of the folding of the strata from the tectonics. Mapping the thickness will help us to map the position of the buried fold. For augering, we only need a small patch of land to stand on. To find it we headed south towards where the valley was uplifted more and might be drier. Not as ideal as the original location, but possible. The next morning we headed farther south and crossed the river valley. It was drier and we noted some potential augering sites. We continued to a location for resistivity. The six of us set up the >350 m long resistivity line, then Céline, Basu and I headed back to try augering while the resistivity data was collected. The augering proved very difficult. We were very slow describing the core that the auger brought up, and while we were doing it the hole would start to collapse. The muddy sediment was very stiff, and we had to hammer the auger in. We only got to 2.7 m when we stopped, nowhere near the depth we needed. Things were pretty discouraging.

Bangladesh and India, Too

Tue, 10/13/2015 - 07:44
Standing in front of the 240-foot tall Qutub Minar, which dates from the 1200s.

Standing in front of the 240-foot tall Qutub Minar, which dates from the 1200s.

I am heading back to Bangladesh, but this time I am stopping in New Delhi before heading to Bengal (West Bengal and Bangladesh). It is the first time that I will be in a part of India that is not adjacent to Bangladesh. Several of us are meeting there to plan for a new project that will span Bangladesh to India to Myanmar. I arrived a few hours before Nano Seeber and Paul Betka and used the time to get a new Indian SIM for my phone. After meeting up, we headed to the guesthouse of the Ministry of Earth Sciences, where we will be staying. If only the U.S. had a cabinet level department for earth sciences. It was difficult to find at night without a Hindi speaker, but we managed.

Over the next few days we had meetings about the project, but also some time for sightseeing, while

The inscription on the Iron Pillar, still unrusted despite being 1600 years old. It mentions Chandragupta's conquest of Bengal.

The inscription on the Iron Pillar, still unrusted despite being 1600 years old. It mentions Chandragupta’s conquest of Bengal.

discussing the project in the car. Most of our meals were vegetarian, and Gandhi’s birthday, which occurred while we were there, is celebrated by eating vegetarian. When two more scientists arrived from Singapore, we started the day by visiting the Qutub Minar, dating back to the 1200s and the arrival of the Muslim Delhi Sultanate, followed by the Mughal Empire in the 1500s. In the Quwwat-ul-Islam mosque, there is the famous Iron Pillar originally erected by Chandragupta in the 4th century, probably at Patna, and brought here much later. Near the beginning of the inscription it says: “in battle with the Vanga countries, he kneaded (and turned) back with (his) breast the enemies who, uniting together came against (him).” Vanga is Bengal, now split into West Bengal in India and Bangladesh.

The massive South Gate entrance to the Taj Mahal complex.

The massive South Gate entrance to the Taj Mahal complex.

 

After mostly finishing discussions, the others decided to take a day trip to Agra to see the Taj Mahal. I was able to change my flight to Kolkata to the following morning and joined them, continuing to talk science on the 4-hour drive. We had to buy the expensive tickets at 750 rupees rather than the 10 rupees the Indians were paying. However, the premium ticket lets us bypass the long lines. The Taj Mahal is the tomb of Mumtaz Mahal,

The Taj Mahal. You can see its enormous size from the line of people waiting to get inside standing on the pedestal. The line completely circled the tomb on this holiday weekend.

The Taj Mahal. You can see its enormous size from the line of people waiting to get inside standing on the pedestal. The line completely circled the tomb on this holiday weekend.

the beloved wife of Shah Jahan, the Mughal Emperor. It was built over 17 years from 1631-1648. She died in childbirth of her 14th child. He was buried there as well when he died in 1668, after being overthrown by his son. I have seen many pictures but was not expecting how enormous the structure is. The entire place is beautiful and enormous with flanking buildings, gardens and gateways. I kept wondering about the cost of building it and how many man-years of India’s peasants financed it. Perhaps this excess was why this was the peak of the Mughal Empire. Within a 100 years, the British were

The entrance to the Red Fort at Agra, a seat of the Mughal Emperors, and still used as by the Indian military.

The entrance to the Red Fort at Agra, a seat of the Mughal Emperors, and still used as by the Indian military.

taking over. Afterwards we went to Agra Fort, which is similarly gigantic, and another seat of the Mughals. There are palaces and a throne inside the red fort with views of the Taj. There are 30 buildings left, the rest having been leveled by the British to erect barracks for their troops. We didn’t get back to our hotel until 11.

I left early the next morning for Kolkata, the British Indian capital until 1911, when they moved it to Delhi. It was done to punish the Bengalis for opposing the

Standing next to a window in the Agra Fort with a view of the Taj Mahal farther down the Yamuna River.

Standing next to a window in the Agra Fort with a view of the Taj Mahal farther down the Yamuna River.

splitting of the Bengal Presidency into more manageable size, which would have cut Bengal in two. I spent the day at Calcutta University then headed back to the airport to fly to Dhaka. At my usual hotel, I met up with Jenn Pickering, a student at Vanderbilt University, and Céline Grall, my postdoc. They were teaching a short course at Dhaka University. I spent the next few days in multiple meetings and making arrangements for a week of fieldwork. It will be good to get out into the countryside.

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A highly decorated marble palace inside the Agra Fort. It has a beautiful fountain built into the floor.

 

Indian Sundarban

Mon, 03/30/2015 - 13:34
Standing in front of the gates to the Queen Victoria Memorial in Kolkata

Standing in front of the gates to the Queen Victoria Memorial in Kolkata

We had a smooth trip to Kolkata with our two taxis amazingly staying together through the traffic. After checking in and freshing up, we went out for dinner and found a great Bengali Restaurant filled mostly with Bangladeshis around the corner. Our hotel turned out to be next to an area where Bangladeshis frequently stay, including Humayun previously. In the morning, he and I went for an early morning walk through the park and saw the Queen Victoria Memorial. Circling back past all the cricket players, we passed Fort William, the original British fort here, and joined Doug and Diane for breakfast. Our car arrived and before heading to the Sundarbans, we drove around to get shots of the Hooghly River. Before the 1600s, this was the main course of the Ganges, but since

A funeral procession arrived to scatter ashes in the Hooghly (Ganges) while we were filming

A funeral procession arrived to scatter ashes in the Hooghly (Ganges) while we were filming

then it shifted to it present course into Bangladesh. We got some shots from the new bridge before being chased off. Then we headed to the Strand to get close to the river. While we were filming, a funeral procession arrived to scatter ashes of the deceased into the river. Once the Holy Ganges, always the Holy Ganges. We couldn’t have planned it better.

Then, off to the Sundarbans. Where we were going was a lot farther than implied. This is because of a difference in naming. In Bangladesh, the Sundarbans is the National Mangrove Forest. The cultivated areas that previously were forest are not considered the Sundarbans. In India, they are. Thus we entered the Sundarbans after 2.5 hrs, but still had that long to go to meet our boat.

Humayun and Diane on the ferry - before it got crowded.

Humayun and Diane on the ferry – before it got crowded.

Admittedly, some of the cultivated areas in India still maintain mangroves outside of the embankments, which is not the case in Bangladesh. Continuing on, we reached literally the end of the road and carried our luggage (including a 50 lb. bag of rock samples) down to a ferry that took us to Gosaba. There, we first got a hand rickshaw to get the luggage across the town, then got two motorized rickshaw trucks to cross to the other side of the island. Finally, we were met by a boat that took us across the river to the eco-lodge where we would stay. After a late (4 pm) lunch we went on a sunset boat ride through some tidal channels. The saw and heard lots of bird and at times the channel became so narrow that we had to push branches away to fit through. The

Doug and Diane following me on their motorized rickshaw truck across Gosaba Island

Doug and Diane following me on their motorized rickshaw truck across Gosaba Island

trees here overhang the channels more than in Bangladesh. We would see further differences tomorrow. After finally showering off, we met other people staying at the eco-lodge, started by 4 cousins including Ajoy, who is leading our trip. The lodge is solar powered, so electricity is limited,but the water was refreshingly cool, not cold. We all heard a performance of Bengali Baul music, recognizing some songs from similar experiences across the border. After dinner, we all went for some local rice wine and then a boat ride to see bioluminescent plankton in a small channel. If you wave your hand in the water dots of light flash.

In the morning, we started at 6 am to have enough time before I had to head for the airport. We picked

A monkey hangs out near the forest station where we picked up our guide.

A monkey hangs out near the forest station where we picked up our guide.

up food and a cook and permits and a guide and finally were ready to enter the forest. In India, no one is allowed off the boat to step on the forest, nor to stay overnight in the forest, even on a boat. Thus many hotels and lodges have sprung up outside the forest for tourists. Many come simply to party and drink. We are very glad to be using an eco-lodge that is more respectful of the land and the local population.

At 8, we finally entered the national forest. Among the differences from the Bangladesh side we noted were the shorter height of the trees in the more saline water, the lack of sediment in the water, and the extent of bank erosion. Where the eastern Sundarbans is fresher with ample sediment carried by the tides due to its proximity to the Ganges-

Doug balancing his camera and his breakfast of puri and dal on the Elmar, our boat for the day

Doug balancing his camera and his breakfast of puri and dal on the Elmar, our boat for the day

Brahmaputra-Meghna River mouth, the western, Indian Sundarbans is more saline and lacks new sediment. Between subsidence and sea level, it is loosing ground. More land is being lost than gained. With the higher salinity, there is also less wildlife. However, there was a tiger sighting this morning. We sailed to the spot, but it was too late, we missed it. Still, we spent 4 hours sailing through tidal channels of different size, eating, and filming. Doug captured the beauty of the Sundarbans and I was interviewed with a great backdrop.

After completing our work, we briefly visited an observation post, we took a short cut through an interior channel in Gosaba Island, dropped off our guide, and crossed the channel to our car. Three hours later, I arrived here at the airport to start my journey home. It was an intense, yet calm 48 hours in West Bengal, the third leg of three very different pieces of this trip.

Overhanging rooks and slumps reveal the much larger amount of erosion and land loss in the Indian Sundarban

Overhanging rooks and slumps reveal the much larger amount of erosion and land loss in the Indian Sundarban

An egret stands tall at the bank of a channel

An egret stands tall at the bank of a channel

A small shrine in the Sundarban to Bon Bibi, the Hindu goddess of forests and streams - and protector from tigers

A small shrine in the Sundarban to Bon Bibi, the Hindu goddess of forests and streams – and protector from tigers

A monitor lizard

A monitor lizard enters a pond

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