By Neil Pederson
As discussed in the previous post, the first half of the field season would be the scientific highlight of the 2011 field season. While we had highlights later on, in terms of finding new stuff, that was it. We knew that would be a highlight because we had a fairly good idea of what was coming next. To our delight, we would be heading back to the small mountain village called Bugant. This is a delight because the family we stay with on trips to the northwestern Khentii Moutains are exemplary in terms of Mongolian generosity.
We knew that we would immediately not only be served fresh tea and plenty of candies and snacks upon our arrival, we also knew that no matter what time ae arrived we would be served a meal. We arrived at about 9 pm and, sure enough, by 9:45 we were fully into our meal.
As always, it was a fun and spirited meal. All the extended family came to visit with us and each other:
We looked forward to the next day’s field work because we were going to one of the most interesting forests we’ve seen in Mongolia – it was an intact, old-growth forest….
However, not all scientific fieldwork is full of exploration and discovery like those fueled by sawdust and mosquito wings. Sometimes, quite often actually, scientific research is monotonous. Even in the field. The work ahead, while in beautiful places, was akin to making the doughnuts. We had to go back to areas we had sampled before, install plots and just core whatever trees fall in those plots. There would be no bird-dogging or seeking out great old trees. What fell in our plots, randomly-located so that they best represented the average forest, ended up being our study trees. Ah, we are not complaining. It is just not as thrilling as the hunt. It feels almost industrial – industrial ecology.
We were a bit leery of this forest as well. When we last sampled in 2009, it turned out to be a cold and wet visit. 2011 turned out to be very much the same. In fact, it turned out to be wetter and colder. It definitely had us shivering in our sleeping bags.
We had expected to complete our work in the first day at the site pictured above. But, after a couple passing showers that were fairly heavy for Mongolia, the temperatures dropped quickly and, well, we started getting cold. We were prepared for this, but somehow this day got to us. We really started shivering and making mistakes. When you start making mistakes when you are cold and wet, that is a good sign to call things off. Not much good can come from continuing. What one can expect is potentially bad data, more mistakes and more mistakes that could become dangerous. So, we called it a day and went fishing.
OK, Baljaa went fishing. Specifically, he went wood fishing. It is a method commonly used to gather firewood in areas with little wood. As you can see, Baljaa, despite being a Mongolian cowboy with more than a hundred horses [he’s a good catch, ladies!], struck out. Time to call in the pro:
As you can see, Baatarbileg is still the master!
What did we cook with this wood? Our clothes, of course:
Actually, the fire and wonderful soup for dinner warmed us up. I do not think the devil actually shivered in his sleeping bag.
The next day turned out to be sunny and we finished off this site. We did get one new discovery: a Mongolian lizard. It got so used to being held, or perhaps it was so hungry from the previous cool, wet day, it itself ‘fished’ for food while being held:
The next day found us heading back to the ‘cement patio’ site. This is a favorite site for us as we had a wonderful Mongolian cookout in 2009. What we had forgotten was how far back we had driven into the Khentii Mountains to find this site.
Talk about monotonous [and desperate…like the beginning of 2011, we were desperate in 2009 to find a goldmine site], we drove 20 km on the road below just to find this site. You can hear below how we had forgotten how far back we drove in 2009.
We hit the slopes as soon as we re-discovered the cement patio; it took about 3 hrs of driving to get to this spot. I had not been up this slope yet as I sampled a different slope in 2009. When Amy said it was steep, I really didn’t know what she meant. As you can see, the slope was nearly a 40% slope:
While in the midst of conducting this industrial ecology, the sky decided to open up again. However, the storm didn’t seem as serious as the prior day and we hunkered down for about 20 minutes. Sure enough, the storm passed as we completed most of our work at this site.
The views from this site are pretty spectacular.
Indeed, it is such a special forest that we will have a special post regarding the state and potential future of this part of the Khentii Mountains.
We headed down the mountain back to the patio and found an incredible patch of berries. There were two types of currants and one type of blueberry. It was delicious. In fact, as it was Chuka’s birthday (our other driver in 2009 and 2011), we gathered as much fruit as possible and re-created our 2009 cook out night to celebrate Chuka. It was a fantastic night until yet another thunderstorm crashed the party and sent us scurrying for the tents. All in all, it was a pretty great night.
There is not too much to report for now about this site. It is definitely another old-growth site that Amy has already written about. We saw some amazing specimens for the main conifer species in Bugant and hiked some cool ridges. We saw wolf and bear scat. We were lucky to spend time in that exceptional Mongolian Wilderness. Here are a couple more pictures.
At 6:30 am on August 5, the R/V Langseth pulled into port in Dutch Harbor, marking the end of our very successful research cruise. Our steam into port from our study area involved a trip through Unimak pass and beautiful views of Aleutian volcanoes, including majestic Shishaldin.
Many things are required to make a research cruise successful, but one of the most important is the people. And we had great people in spades. The Langseth’s crew and technical staff are excellent: extremely competent, hard working and dedicated. Throughout our endeavor offshore Alaska, there were challenges: temperamental aging scientific equipment, tricky maneuvering very close to the coast line, subpar weather, etc. All of these obstacles (and more) were handled admirably and without complaints. Protected species observers cheerfully spent long, cold hours exposed to the elements on the observation tower watching for mammals to ensure that we operated responsibly. Our science party was also terrific; everyone worked hard and worked well together. And if you’re going to spend 38 days at sea with a group of people, it doesn’t hurt if they are nice and friendly in addition to being smart, competent and hard working. And it was a uniformly nice and friendly crowd aboard our cruise, MGL1110. Our efforts would also not be possible without support ashore from Lamont’s Marine Office and the National Science Foundation. The evening of our arrival in Dutch Harbor, we celebrated the completion of our successful cruise and toasted (repeatedly…) the people who made it possible at a post-cruise party at the Harbor View Bar and Grill.
Many people flew home after our arrival in Dutch Harbor, but not me! (At least not yet). Katie Keranen and I will recover the seismometers we deployed way back at the beginning of the summer. Hopefully these instruments recorded lots of earthquakes as well as our offshore experiment, and hopefully they were not disturbed or damaged by curious wildlife (including people!). An Anchorage-bound flight from Dutch Harbor dropped me off in Cold Bay on Aug 6, where I rendezvoused with Katie. After the plane landed, the stewardess asked for our “Cold Bay passenger” to disembark. Passenger. Singular. I filed past all the folks heading to Anchorage and beyond. Unlike them, I will linger a little longer on the beautiful Alaska Peninsula.
1 August 2011 – Final Dispatch from Arequipa, Peru
Now, after more than six weeks trawling the Peruvian Andes in search of palaeoclimate clues, we’re out of time. More than that, rather exhausted, too. Since we left Ampato, Matt has gone back to Tacoma, leaving Kurt and me to visit potential calibration sites near Coropuna. The objective of that ongoing work is to refine the cosmogenic surface-exposure method for the tropics, thereby improving the precision of new and existing datasets. It’s therefore a very high priority.
Many hours of rough driving over destroyed mining roads brought us finally to an isolated copper mine north of Coropuna. There, having waded through piles of bureaucratic red tape and caught a wretched cold from a forlorn security guard, I spent a few days exploring potentially suitable lava flows, while Kurt went off in search of palaeoindian lithics and rock shelters. It’s a fine spot, with amazing volcanic features and stunning views of Coropuna, and boasting more viscacha (a type of Andean rodent/rabbit/monkey mix) per square meter than anywhere else on Earth. It’s too early to say whether this area will prove useful, but the search itself certainly constituted a worthy adventure.
With our last samples collected and bagged, these last few days have been a whirlwind of tying up loose ends, such as returning the vehicle, shipping 100 kg of stones back to Lamont, and eating as much as possible. Arequipa is a lovely city, and a fine place to call base camp, but with so many chores to be done it was with a great measure of relief that we climbed onto the plane again at the foot of Volcan Misti, bound for Lima and, ultimately, the northern city of Huaraz. I could go on for pages about the splendours of that place, tucked up in the stupendous Cordillera Blanca, but I shall save it for another year. As for now, I shall swap icy peaks, tents, and blue skies for the record-setting heat of urban New York, while Kurt heads back south to Arequipa for a while longer to complete archaeologic lab work there. This has been a fantastic season, our most successful yet – I hope you’ve enjoyed following along from a safe distance.
Although we still have ~3 days of data collection aboard the R/V Langseth to go before we pull in our equipment and head for port, we are already drowning in beautiful seismic data. Following each pulse from the air gun array, the two 8-km-long streamers listen for returning sound waves for 22 seconds. This is enough time for the sound waves to travel down through the water, sediments, crust and upper mantle and back again. Arriving sound waves are recorded on a total of 1272 separate pressure sensors along the streamers, producing about 60 Mb of data for each pulse. Repeat this every 25 seconds for 3 weeks, and you end up with a pile of data! We have already recorded over 2.5 terabytes (2500 gigabytes!) of raw seismic data. This does not include other large datasets that we are simultaneously acquiring, such as detailed bathymetric mapping of the seafloor.
Once we obtain the raw data, our eager scientific party cannot resist beginning some rudimentary analysis, thereby generating even more large data files that take up yet more disk space. In search of instant gratification, we use some quick and dirty processing steps to produce preliminary images from our data and get a first peek at the structures beneath the seafloor. This is standard procedure on cruises aboard the Langseth and other seismic ships. Often, such images reveal very little; careful analysis of seismic data to create clear and accurate images of earth structures takes years. But in our case, the data are of such high quality that spectacular features are evident even in these rough first images, including the plate boundary and other faults. This assures us that hard work on the data following the cruise will produce very exciting results.
One of the key shipboard tasks is determining the position of the gear in the water and combining this navigational information with the raw data. Our streamers are 12 m under the sea surface, so we cannot simply attach tons of GPS sensors to them to figure out where they are at any given time. Instead, the Langseth’s infatigable Chief Navigator, David Martinson, works out the locations of the streamers using GPS’s at the beginnings and ends, a series of compasses spaced along the streamers, and several “acoustic nets,” sets of instruments that give the distances between the streamers at key positions. He can determine the positions of our two unruly 8-km-long cables to within ~5 m or less at any given time – amazing!
We also produce initial images of seafloor topography from bathymetry data. At sea we begin the arduous task of manually editing vast quantities of the data, but the effort pays off. Careful analysis of these high-resolution data can reveal faults that cut through the seafloor, seamounts, and sedimentary features.
20th July – Dispatch from Nevado Ampato, Andes
Our camp is at 5045 m on the dusty slopes of Ampato, an extinct, ice-clad volcano in the Western Cordillera. This is the very mountain from which Juanita, the famous Incan ‘ice maiden’, was plucked back in 1995. The tents are clustered in the lee of a large glacial erratic and, now the clouds have cleared, the view is second to none, taking in the dry plains far below and myriad volcanic peaks in every direction. Of these, only distant Ubinas shows any activity, letting slip the occasional cloud of ash. To complete the picture, behind us are the hulking masses of 6380 m-high Ampato and it’s smaller yet more violent brother, Sabancaya.
Yes, it is a fine place to call home as we begin mapping and sampling moraines of late-glacial and Holocene age in this part of the world. For added interest, the landscape here is dominated by sinuous lava flows that extend many kilometres from Sabancaya’s summit to the puna below. These black tongues of rock are both grotesque and strangely beautiful, especially when dusted with snow.
Speaking of dust, or rather sand, recently it has become a bit of a plague. Given the propensity for volcanic activity in this part of the Andes, our peaks camp is located on a surface of black sand, dust, and gravel, much of which becomes airborne during the fierce wind storms we’ve been experiencing. Just yesterday, as we were working on the youngest and highest moraines on Ampato, we happened to be suffering through a particularly bumpy spell of weather.The wind was funnelling down from the peak and pushing around waves of drifting snow. It was truly invigorating! From our high perch, though, we watched as plumes of dust were lifted by the wind from the plateau below, forming a brown blanket that came to obscure all but the highest peaks before spreading south to torment the city of Arequipa. By the time we returned to our camp that afternoon, our world was one of particulate matter. Sand in our food, sand in our tents, sleeping bags, and clothes. Worst of all, there was sand in my tea. But then, they always did say it takes a lot of grit to be a glacial geologist.
For the last nine days, we have been underway acquiring seismic reflection data to study a plate tectonic boundary offshore Alaska with the R/V Marcus G. Langseth. Now that the initial excitement of deploying all of our seismic gear and watching the first sound waves arrive on our two 8-km-long streamers has faded, we have settled into a routine of watches and standard shipboard data processing. Meals, sleep and leisure also take on predictable patterns. Each day resembles the one before, and they all start to blend together. This may sound rather humdrum, but an uneventful day at sea is normally a successful and productive one (as one of the undergraduate watchstanders noted). When something “exciting” happens, it is usually not good.
Happily, a large proportion of our nine days have been blissfully boring, but we have had our share of happenings. Excitement takes the form of equipment failures, bad weather and marine mammals. Acquiring marine seismic reflection data is a fantastically complex undertaking involving a lot of sophisticated, interdependent gear, so things can and do go wrong once in a while. A few nights ago, one of our streamers sank too deep, causing a “streamer recovery device” (a specialized airbag) to deploy and float the streamer to the surface. The next morning, a team used the workboat to visit the problematic streamer section and remove the airbag. On a few other occasions, I have received phone calls in the middle of the night summoning me from my cabin to the main lab to discuss other equipment hiccups – no one ever calls at 3 a.m. to let you know that everything is going swell.
Whales are beautiful and majestic, and we have been treated to numerous sightings, but we try to keep our distance. Since we are creating sound waves to image the earth, and marine mammals use sound to navigate and communicate with one another, our activities might disturb them. A team of protected species observers (PSO) watches for mammals, and we suspend operations if a mammal comes too close. Yesterday morning, we found ourselves surrounded by three species of whales, including a rare Northern Pacific Right Whale – an amazing sight, but it prevented us from collecting data for nearly four hours.
Of course there are notable exceptions to the “excitement is bad” maxim, the most important of which is the science! We use our new data to create very preliminary images of the structures below the seafloor as we go, and they have revealed some intriguing and surprising features. A regular sight in the main lab is a group of people gathered around a computer screen or a large paper plot, talking and pointing excitedly. We have a lot of hard work ahead after the cruise to obtain concrete results, but it’s exhilarating to glimpse faults, sediments and other structures in our data for the first time and ponder what they might be telling us about this active plate tectonic boundary. Even after spending a total of nine months at sea on ten research cruises over my career, the excitement of new data has definitely not worn off.
One of the core objectives of our project is to image the part of the plate tectonic boundary that locks up and then ruptures to produce great earthquakes. In the Aleutian subduction zone, the Pacific plate is being thrust northwards underneath the North American plate. To examine deep parts of the interface between these plates, we need to go as far north (and as close to the coast) as possible. This is easier said than done. We are towing a lot of scientific equipment behind the ship, including two 8-km-long cables (streamers) filled with pressure sensors, so approaching the coast and making turns is complicated and requires special attention to safeguard our gear. The southern edge of the Alaska Peninsula is rugged and flanked by lots of small jagged islands and shallow features just below the surface of the ocean. Currents and water density can vary locally near the coast, which could affect the positions and depths of our streamers behind the ship. And there is more fishing activity close to the coast, and thus increased risk of tangling seismic gear with fishing lines and nets. To reduce the risk, we scouted all of the trickiest parts of our survey ahead of time before we deployed the streamers, and we monitor the currents and fishing as we approach the coast. Captain Jim O’Loughlin, Chief Science Officer Robert Steinhaus, and the Langseth’s other crew and technical staff have a tremendous amount of experience and skill in maneuvering in tight spots while towing seismic equipment.
We recently completed one of our closest approaches to land near Unga, one of the Shumagin islands. At the apex of the turn, our 8-km-long (5-mile-long) streamers came within less than a mile of the coast. Due to some early difficulties with our equipment and an abundance of marine mammals, we had to make several attempts to collect data on the landward part of the line (and thus several passes near the shoreline). I held my breath and watched our third (and final) pass from the bridge. After the ship and gear passed safely through the most harrowing part of the turn, the captain turned to me and asked, “We’re not going to do this again, are we?” Thankfully not! At least not here. But there are several other important parts of our survey ahead that will require close approaches to the coast to image critical parts of the plate tectonic boundary. As with this near-shore encounter, we will rely on the skill and experience of the mates and the technical staff, as well as a little luck.
14th July – Dispatch from Chivay, Peru
After a busy few weeks in the Cordillera Carabaya, we’ve said goodbye to the snowy, tempestuous climate of the eastern Andes and are moving west to the desert of Arequipa. Here the mountains are massive, isolated volcanoes, many of which exceed 6000 m in elevation. In fact, Coropuna is the third highest mountain in Peru and certainly the most sprawling. It’s a landscape dominated by lava and aridity, and populated only by wild vicuna, condors, and a few hardy llama herders. Our first stop was Chivay, a lovely little town nestled in the upper Colca Canyon under the shadow of the enormous Nevado Ampato. We spent a day there recharging, replenishing our stocks and generally avoiding the blizzard on the plateau above. This being the desert, we had not anticipated that the bad weather would follow us west, but evidently it is possible. There is nothing quite like driving through the night, down the side of a canyon, in a snowstorm to focus the mind!
Our work here involves mapping both the glacial deposits and Holocene lavas on the two volcanoes, Ampato and Sabancaya. Though in sight of Arequipa, the place is actually more remote than Coropuna, accessible only via a two-hour drive down a washed out dirt road. This is a new region for us and so it promises to be a fascinating few days of exploring.
On July 11, we marked the successful completion of the first phase of our project and embarked on the second. Part 1 involved deploying ocean bottom seismometers and recording air-gun-generated sound waves. We successfully retrieved all of the OBS’s, and the data that they recorded look very exciting at first blush (and contain some surprises!). Part 2 involves towing two 8-km-long cables (or streamers) filled with pressure sensors behind the R/V Langseth, which will also record sound waves from the Langseth’s airgun array. Changing gears in terms of scientific activities also involved changes to our science party; we swapped personnel in Sand Point on a beautiful sunny evening. The excellent OBS team from Scripps departed on the Langseth‘s zodiak, and we were joined by new reinforcements. The newcomers included five undergraduate students from Columbia University, who are also blogging about their experiences at sea.
Just two hours after taking on our new personnel, we started deploying seismic gear – a very quick transition! Our seismic streamers are stored on gigantic spools, which unreel cable off the back of the ship into the ocean. A large buoy is affixed to the end of the streamer, and ‘birds’ are attached along its length, which can be used to control the depth of the streamer. Large paravanes hold the streamers apart; these are like large kites flying in the water off the back corners of the ship.
Deploying miles of streamer and the other attending gear is an impressively long and complicated undertaking. We started over two days ago, and have been working around the clock in shifts ever since. Many repairs and adjustments are made to the gear as it’s deployed. The streamer is divided into 150-m-long sections connected by modules; both sections and modules can fail and need to be replaced. Replacing a 150-m-long section of cable is an arduous task involving major manual labor by teams of ~5-6 people. But we are nearing the finish line; as I write, the last kilometer of the second streamer is going over the back of the boat. Fingers crossed that the deployment will soon be complete and the data collecting can begin!
10th July – Dispatch from Nevado Tolqueri, Cordillera Carabaya, Andes
We have acquired a dog, ¨”Mooch”. Walking back to camp yesterday, amid driving snow and fully laden with rock samples, there he was exploring what passes for our kitchen. Unlike most Andean dogs – ferocious beasts trained to keep geologists from harassing the livestock – this one is a cheerful soul, happy to hang around and be fed whatever is going, and always up for affection. Where he came from we don´t know. We´re camping at 4750 m in a shallow valley between moraines that keeps the worst of the wind at bay.
There is nothing to burn here and so the nights are frigid, though the view of the entire Cordillera Carabaya, as far as Bolivia, is superb. There are a few hardy souls farming alpacas up here, so presumably the canine comes from one of those, but nobody seems to be missing him. Last night he cleaned our plates and pans, as the snow fell all around, and this morning he was still there. I awoke to find Mooch curled up by the stoves, tucked up in a snowy ball. He immediately perked up once I arrived and waited with agreeable patience as we made a sort of rice pudding for breakfast. Then, with breakfast done, he followed Matt and me as we went off to collect a few more samples for surface-exposure dating. It will be sad to leave the pup, but we must head west soon to the desert Andes. And as Kurt noted, a high-altitude dog accustomed to sleep in the snow would hardly fare well in subtropical New York!
A word on the weather here. It´s taken a turn for the worse. We´ve been working on LGM moraines beneath Nevado Tolqueri and have made great strides there, collecting tens of samples from a fantastic sequence of moraines. But a drawn out storm has engulfed us from the east, appearing first as enormous thunder clouds and transitioning into incessant snow and high wind. It´s not quite what we´d expected but what can you do? It´s times like these we wish we had a kitchen tent instead of a patch of open mountain for cooking. It will be interesting to see how far west this system goes. In the meantime, we will try to keep our feet dry and the dog fed.
4th July – Dispatch from the Andes
Thanks in large part to Matt, an undergraduate from Pacific Lutheran University in Washington, we now have more than sixty samples for surface-exposure dating. This is no easy feat, for collecting these samples requires a great deal of hammering on granite boulders with nothing more than a hammer and chisel. There are other ways of doing it, such as using small explosive charges, rock saws, or splitting wedges, but we find that good old-fashioned hammering is by far the safest way. I say ‘we’ but really this means Matt. He has a gift for removing large amounts of rock, be it a soft shale or the hardest quartzite. And best of all, he doesn´t complain. So in all, we have sixty four samples from the Aricoma region, from moraines of all ages. In addition to the hammering, the process includes detailed descriptions of each boulder and measurement of location, altitude, and how much of the surrounding sky is obscured by mountains. It can take a while but we have it down to an art now, as the ton or so of granite in the back of our vehicle attests!
We´re also collecting sediment cores from bogs within the moraines, so as to provide radiocarbon ages for the deposits. Just yesterday we extracted a two-meter core from a basin near camp that lies between two long moraine ridges. It was a messy business, taking the three of us to punch the core barrel through the malodorous slime and into the stiff glacial clay, going as and as far as the rocks below. When all was said and done, each of us was fairly bloody and covered with ancient mud, but the core was extracted and the day was ours. Now the core is neatly contained in plastic tubing, sealed from the air and ready for shipment to Lamont where it will be analyzed.
After leaving our seismometers on the seafloor offshore Alaska for a few days to record sound waves generated by the air guns of the R/V Langseth, we returned to collect them. The recovery of OBS always involves a certain amount of suspense. Despite all of the advanced engineering and planning that goes into these instruments, it is an endeavor with inherent risk, and things can and do go wrong sometimes: one or more of the glass balls that make the OBS float could implode; the acoustic communication with the instrument could fail; it might be stuck on the seafloor for one reason or another; it could have been accidentally dragged off by trawlers. All of these thoughts ran through my mind at each site as we waited for the instrument to come to the surface.
To recover the OBS, we return to the place where we deployed it and communicate with it acoustically. We send it a command to release from its anchor and float back to the surface. The OBS rises through the water at 45 meters per minute, so the wait can be long if the water is deep. Some of ours were 5500 m below the surface! The instruments can also drift away from their original deployment location on the way down or the way back up due to ocean currents. When they arrive at the surface, we can spot their orange flags and strobe lights; they also send out radio signals.
Despite all the technology required to place a seismometer many miles below the ocean on the seafloor and summon it back to the surface, many aspects of actually plucking an OBS out of the ocean and pulling it on deck are remarkably low tech (yet still very impressive). Once we have spotted the OBS floating on the surface, the ship drives alongside. It is akin to driving your car up next to a ping-pong ball. People lean over the starboard side of the Langseth and attempt to attach a hook with rope to the bars on top of the OBS using a long pole. Its not always easy since the OBS is bobbing up and down in the waves. Once we hook it, we can attach a rope to the winch and haul the OBS onboard. Sometimes, OBS’s bring back surprises – an octopus returned with one of our OBS’s! He was alive and healthy, so we returned him to the sea (though some lobbied to keep him for lunch…)
Happily, we recovered 100% of our OBS’s and have started to (briefly!) pore over the data they recorded while they were on the seafloor. We can see the arrivals of sound waves from our air guns as well as lots of earthquakes, some very close and others far away. It would be delightful to dig into the analysis of these data immediately, but it must wait – there is more data to collect! We’re currently deploying OBS’s along our second profile.
On July 2, we finished deploying over twenty ocean-bottom seismometers as a part of our marine expedition to study a major tectonic boundary offshore Alaska. Ocean bottom seismometers (OBS’s) are autonomous instruments that sit on the seafloor and record sound waves traveling through the earth and the water. Floats made from glass balls and syntactic foam make each OBS buoyant, but an anchor holds it on the seafloor during the study. We communicate with each OBS acoustically, allowing us to send it a command to release from its anchor when we are ready to recover it.
For our project, we are placing OBS’s from Scripps Institution of Oceanography on the seafloor along two lines that span the major offshore fault zone. Immediately prior to deployment, we assemble the main components of each OBS on deck while the ship transits between sites. When we arrive at the deployment site, the ship slows down, and the OBS is lifted over the side of the vessel and into the water with a large crane. We release it, and it sinks to the sea floor. Thanks to the skill and hard work of the Scripps OBS team and the ship’s crew, we were able to deploy one OBS every hour, which is very efficient!
The larger the distance between the sound source (earthquakes or air guns) and the seismometer, the deeper into the earth the recorded sound waves travel. OBS are very sensitive and not attached to the vessel, so they can record sound waves generated very far away by earthquakes or air guns (commonly >200 km). Because we want to examine deep fault zones that cause large earthquakes off Alaska, OBS are a critical part of our effort.
In a few days, after we steam back over the OBS’s generating sound waves with our air guns, we will return to retrieve them. Even after ten years of working with ocean-bottom seismometers, it never ceases to amaze me that we can throw a bundle of very sophisticated electronics over the side of the ship and hope to pick it up and retrieve useful information from it. We are very excited about the new insights that will be provided by the data recorded on these instruments…
Each morning starts the same in the Andes: the frost is heavy on the insides of our tents and falls with the slightest movement, while the realization that it´s going to be a freezing exit from the sleeping bag is tempered by gratitude that the thirteen hour night is over. Yes, sunrise in the Andes is a momentous occasion each day, one that feels a million miles away from home. Kurt typically is the first up and dutifully begins brewing fine coffee on the camp stove. Matt emerges shortly thereafter. Nobody says a word, we just stand around in the frost like cold lizards – or maybe zombies – until the sun arrives to warm us. By midday it is fearsomely hot in the sun and the down clothing is replaced by sandals and wide-brimmed hats. Then, just as one is getting used to the idea of a nice afternoon siesta, the sun drops behind the skyline and the climate is icy once again.
One thing I am reminded of daily is that here in the Cordillera Carabaya, unlike in the western Andes, we are never alone. The moraines we investigate and the valleys we explore are someone´s backyard. Herds of alpacas swamp our campsite, followed by ferocious dogs, and mining trucks, laden with gold ore from Limbani, compete with our 4 x 4 for road space. We´ve met some interesting folk here, too, such as the toothless, Quechua-speaking alpaca herder high on a moraine, to school children asking us how to pronounce derogatory words in English.
We´ve been at Aricoma a week now and, I am pleased to report, have a lot to show for it. In addition to scratty, dusty beards and admirable tans, we´ve mapped and sampled glacial deposits young and old, from the last glacial maximum right up to the present day. This work has taken us up into the high valleys, where the last remnants of glacier ice are tucked away in shady recesses above 5000 m elevation. Here, we are surrounded by imposing peaks and deep, glacial lakes of indescribable beauty. It truly is a geologist´s dream, if a cold one.
Yesterday evening, we left Kodiak aboard the R/V Marcus G. Langseth and began our 38-day-long research cruise offshore Alaska. As we left port, we were treated to clear skies, calm seas and spectacular views of Kodiak – dark grey mountains tipped with snow emerging from the lush green landscape.
Although Kodiak offered beautiful sights and delicious seafood (like locally caught halibut and scallops), our science party was eager to leave for sea. We have been waiting for the opportunity to collect these data for a long time. Our expedition was originally planned for September 2010, but there were delays in the Langseth’s schedule that would have required us to conduct our offshore study later in the fall, when the weather deteriorates. Rough seas make some marine operations more dangerous and can also reduce the quality of the data. We opted to postpone until the summer of 2011 to secure a better part of the limited weather window in this remote and northerly region.
But for some members of our science party, the wait has been much longer. In 2003, my colleagues Mladen Nedimović, Spahr Webb and the late, great John Diebold first conceived the idea for this study. Although many other scientists in our community and the National Science Foundation were very supportive of this project, it was scuppered by limited science funding and the temporary lack of a US academic seismic vessel between retiring the R/V Ewing and acquiring the R/V Langseth. But sometimes good things come to those who wait, and at long last we are setting out…
June 22, 2011
After a very cold morning in Crucero, the sun burned off the clouds to reveal the black peaks of the Cordillera Carabaya to the east. There´s not so much snow left on the hills these days, just a few glacier patches clinging to the south faces of the highest summits. Nonetheless, the vista is spectacular and Crucero by day is quite colourful, with fantastically painted buildings spaced around a busy plaza.
We had a stroke of luck today when we ran into a local man by the name of Demitrio. Demitrio was an enormous help back in 2009, helping us gain access to Aricoma and the hills beyond. This year he was all smiles and quickly ushered us into the mayor´s office, where Kurt explained (in his superior spanish) what we were doing and the objectives of our project. Now, with the town´s blessing and a signed, official-looking letter in hand, we´re about to head off to our camp at 4600 m on the shore of Aricoma.
This morning we also made our final gear acquisitions – some plastic piping to transport sediment cores back to the US for analysis. These we had to cut into sections with a small hacksaw and then split in half, a delicate and quite tiring job at this altitude, but necessary. Now, vamos a trabajar!
Seven days and eleven flights after we arrived in Alaska, we finished deploying our seismic stations onshore. Our final constellation of stations differs a little from our original plan (as always happens with field work), but achieves our main goal of instrumenting the part of the Alaska Peninsula that is nearest to our planned offshore work on the R/V Langseth. We installed our final seismic station yesterday in aptly named Cold Bay. This town sits next to a large bay with the same name and is famous for its wind. The most common damages sustained by cars and trucks here are jack-knifed doors from the wind (as I learned the hard way!).
As luck would have it, we finished deploying our seismometers just in time to catch a large earthquake (magnitude 7.2) that occurred farther west in the Aleutians around the Fox Islands. Of course we would love to immediately look at the recordings of this event on our stations, but we must wait patiently until August when we return to recover them. Many permanent seismic stations are telemetered, so data are transmitted back to scientists in near real time. But for temporary deployments like ours, the data are just written to a local disk and thus must be downloaded in person at the station.
We did have the chance to take a sneak peak at some of the data recorded at our station in Nelson Lagoon during the first few days of our deployment. Reassuringly, we saw evidence for several local earthquakes in these data, including a magnitude 3.1 near Sand Point.
Now that the onshore deployment is finished, Katie and Guy departed for home, and I soaked in some sunshine in Anchorage and started looking ahead to our upcoming research cruise. Tonight I fly to Kodiak to await the arrival of the R/V Langseth and our shipboard science party…
June 20, 2011
This morning we left Arequipa and the comforts of the tourist trail, driving east across the puna towards the Andes proper. Our route took us along the newly constructed Caraterra Interoceanica – a highway linking the Pacific coast of Peru to ports in Brazil – and up to elevations of 4700 m. Along the way we passed the smoking Volcan Ubinas, Peru’s most active volcano, and the enormous inland sea of Lake Titicaca. As we approached the Cordillera Carabaya, which bounds the puna to the east, the clouds increased and the landscape changed dramatically, from desert to grassland.
In recent weeks, social unrest related to the opening of a gold mine near the city of Puno has resulted in violent protests. Though we were able to avoid Puno as we travelled east, this sort of anti-mining sentiment underlines the importance of obtaining the blessing of locals to carry out our research on their land.
By mid afternoon we arrived in the small town of Crucero, located at 4100 m beneath Laguna Aricoma – our first site. This town is, frankly, a bit grim, consisting of grey concrete houses and rubble streets, and located on a windswept plain below the mountains. Nonetheless, we’ll spend the night here in order to meet with the governor tomorrow. Fingers crossed that he will remember us and grant us permission once again to roam around. To end on a light note, the Cordillera Carabaya happens to be the alpaca centre of the universe, and so there is a high chance that one of these cute fluffy camelids will end up on our dinner plates tonight.
19th June 2011
What a difference a day makes! We’ve said goodbye to the sprawling metropolis of Lima and now are happily settled in Arequipa – the White City. This name refers to the white sillar rock used in the construction of the old colonial city and which is in fact a pyroclastic deposit from the volcanoes towering above us. From our hotel room I can see the massive bell-shaped peak of El Misti (5800 m), the only active volcano of the group, and it’s looking particularly snowy this year. In fact, flying in to Arequipa, I was surprised to see so much cloud. Normally, with this being the dry season, the sky in this desert region is blue and the mountains dry. Perhaps we should prepare for some wet, snowy field work!
Thankfully, nothing has changed at La Casa de Melgar, our Arequipa base, and I dug out my sampling tools from where I’d stashed them last year, a little dusty but in perfect working order. The rest of our gear, due to its incredible weight, is making its way slowly from Lima by road and should be here tomorrow morning. As for Matt, we found him in the airport, looking surprisingly fresh-faced after his red-eye flight, and so our field team is now complete.
We’ll spend the rest of the day organizing our transport and, in the interests of science, sampling the rather incredible local cuisine.
Every field location comes with logistical hurdles, and the Alaska Peninsula is no exception. Weather, wildlife and modes of transport pose the greatest challenges. We are hardly the first scientists to encounter these: Lamont-Doherty Earth Observatory has a long, rich history of collecting seismic data in this region (e.g., Shumagin Seismic Network, which ran for >20 years), and many groups continue to collect geophysical data here today.
The Alaska Peninsula is too rugged and wild for a network of roads, so planes, helicopters or boats are the only transportation options. We opted for planes, which immediately imposed a restriction on the locations of our seismic stations: they must be near airstrips. Happily, the Peninsula is sprinkled with small communities and lodges with airstrips, most of which lie close to the Pacific or Bering coasts rather than in the remote interior. Back in the office before our deployment, we chose the most ideally located airstrips for our stations and connected the dots between them with the most efficient possible flight plans. But, our plans quickly changed once we were in the field. The weather dictates when and where you can fly each day, and it varies dramatically. We have been lucky enough to have several clear days (even saw some blue skies and sunshine!), but other days we have been grounded by weather and wiled away the time indoors at the inn in Nelson Lagoon.
Once we arrive in each location, we need a quiet, safe place to install our equipment and a ride from the airstrip. On both counts, local communities have been unwaveringly helpful and friendly. The two school districts here kindly granted us permission to install our seismic stations at any of their schools, and we also obtained permission to place equipment at various lodges and village offices. Residents volunteered to take our gear and us from the airstrip to our sites. In one town, our pilot made a general plea over the radio: “Is anyone listening on Channel 3? I’m here at the airstrip with scientists who need a ride to the school”. Someone answered immediately and picked us up 5 minutes later.
Many of our sites are in spectacular places near remote lodges or in towns nestled between mountains and the ocean. All of them are home to impressive wild life that poses a risk to our equipment, particularly bears. We can protect the equipment against curious small animals but fully bear-proofing a station for a short (two-month-long) deployment is not feasible. Instead, we hope that placing our stations in villages (rather than in the wild) will provide some protection, but we will also need good luck. Fingers crossed…