The back of the lab where most of the preprocessing and quality control is done.
Being at sea again allows me to look back at our extended stay in Vigo (Galicia). The port city of Vigo is a unique and beautiful place. The summer months are particularly nice as this part of the Atlantic coast is rainy most of the year. Vigo is just about 2hrs north of Porto (Port wine), which is in Portugal. The proximity to Portugal and the fact that in the past teaching the English language was not stressed within the school system leads to a population that speaks a mixture of Portuguese and Spanish, but not much English. As a result my (poor) Spanish was definitely put to the test as well as my ability to communicate using what are best described as elementary level sketches.
What Vigoites lack in English they make up in hospitality and a relaxed outlook on life. In short, the idea of a "siesta" is not lost on them. While the bars (and there are hundreds if not thousands) are usually open, the restaurants do not open until 8:30 p.m., and generally not at all on Sunday. However, we did manage to find one that is, and it happened to have very good (and cheap) Tapas. Although off the beaten path it quickly became one of our favorites.
A view of Cies from Playa Samil with faults indicated by the arrows.The part that we had been so patiently waiting for arrived after almost 3 weeks in this unique place. While I will not miss being in port, I am happy to have had the chance to see and experience this part of the world as it truly is a beautiful place.
It has been a while since we last updated this blog. The reasons are many. The primary reason for the delay is that we have had singular focus in launching our next project, a project that for many is a dream come true.
Before we launch into that and officially start the 2013 field season, let’s do a quick recap of our team’s efforts since last August.
Our academic year started with a bang: our new research project, which was an unexpected off shoot of our efforts to study climate, fire, and forest ecology, was funded by the National Science Foundation in September 2012.
Since then, our team has spent much time presenting prior results, new preliminary results and processing samples. Many, many samples.
First, kudos to Nicole Davi work improving a tree-ring based reconstruction of the Kherlen Gol in Mongolia (gol = river). Many of the chronologies used were collected between 2009 & 2011 as a part of the Climate, Fire, and Forest Ecology project. The new work, “Is eastern Mongolia drying? A long-term perspective of a multi-decadal trend” can be found here.
Second, we need to congratulate Cari Leland on persisting and publishing the first paper from her thesis: “A hydroclimatic regionalization of central Mongolia as inferred from tree rings “ – link
Cari’s effort set the stage for our second paper on the climate history of the Mongol Breadbasket: “Three centuries of shifting hydroclimatic regimes across the Mongolian Breadbasket“ – link
Finally, Tom Saladyga got a nice piece of his dissertation published with the article, “Privatization, Drought, and Fire Exclusion in the Tuul River Watershed, Mongolia“ – link
We have a few manuscripts in development from our Climate, Fire, and Forest history project, which ends in 2013. And, we are very happy that Byambaa is on the doorstep of completing her dissertation. This project is coming to a very nice completion and we are thrilled.
We are equally thrilled with the start of our new project, “Pluvials, Droughts, Energetics, and the Mongol Empire”. We’ve gotten a silly amount of press here, here, here, here, and here – it has been great. Both institutions have made nice videos and overviews of the project: here is an example of WVU‘s and here is LDEO‘s. Awareness of this project has been widespread. We meet new scholars from various parts of the world and it seems they are already familiar with the new study. Neil presented preliminary results at the PAGES meeting in Goa, India – that was hard work
Amy Hessl garnered two invites based upon our work. The first was a workshop primarily populated with historians on migration and empires across Eurasia. The setting and out-discipline experience was fantastic. The second was an archeology-based workshop on Chinggis Khaan in Jerusalem – sounds like that was equally hard work!
We are now gathering in Ulaanbaatar to launch the first season of ‘complete’ field work. By complete fieldwork, I mean that we will not only be collecting tree cores and cross-sections from dead trees, but Avery Shinneman Cook will be leading the effort in collecting lake sediments in central Mongolia to better understand long-term environmental history and the impact of the Mongol Empire on the landscape in and around the ancient capitol, Karakorum.
Prior to that, we will hold a 4-day workshop introducing ourselves to our wonderful and diverse team (a dream team? Besides Amy Hessl and Neil Pederson, team members include: Baatarbileg Nachin, Hanchin Tian, Nicola Di Cosmo, Avery Shinneman Cook, Kevin Anchukaitis, Oyunsanaa Byambasuren, and PhD students, Caroline Leland and John Quinn Burkhart) and their specific research. We will visit historical sites and lakes to begin the discussion on how to address some questions originally posed in our grant: did the rise of the Mongol Empire, driven literally by horsepower, benefit from an abundant climate and a surplus of ecosystem energy? Did the construction of the Mongol population, army, and herds of grazers significantly impact the landscape? Answers to the ful climatic context of the Mongol Empire has been a primary goal of the Mongolian-American Tree-RIng Project, (MATRIP) since the mid-1990s. We finally have the chance to address these questions. We do not know the answers yet, but stay tuned.
Brief Observations on an alternative approach to Mongolia:
This is my 9th trip to Mongolia. It is hard to believe that I have visited this far-away land so many times. But, when I smell the steppe as we enter the airport, I relax and hit a new mode that is akin to putting on old slippers. I go through customs with nary a concern knowing that Baatar will be waiting for me with a warm greeting and hug. The drive to UB is filled with the same conversation – “How are you? How is Mongolia? How are things going? How is your family? How are your students? My, Mongolia has changed“. It is wonderful.
What changed for me this year was how I got to Mongolia. I typically venture west and enter through eastern Asia. This time, I traveled east, stopping in Turkey, re-fueling in Bishkek, and then flying over western China and western Mongolia.
The sky was clear upon entering western China and the scenery was stunning. Really. I stopped my movie and just drooled out the window [akin to a dog?]. It adds a few hours of travel time at most, but I’d do it again.
Scenes of Going East to go East
A new study in the journal Nature provides fresh insight into deep-earth processes driving apart huge sections of the earth’s crust. The process, called rifting, mostly takes place on seabeds, but can be seen in a few places on land—nowhere more visibly than in the Afar region of northern Ethiopia. (See the slideshow below.) Here, earthquakes and volcanoes have rent the surface over some 30 million years, forming part of Africa’s Great Rift Valley. What causes this, and does it resemble the processes on the seafloor, as many geologists think?
The study suggests that conventional ideas may be wrong. Past calculations done by scientists predict that the solid rock under the Afar should be stretching and thinning substantially as the continent tears apart; thus molten rock should not have far to travel to the surface. Led by David Ferguson, a postdoctoral researcher at Columbia University’s Lamont-Doherty Earth Observatory, researchers analyzed the chemical makeup of lava chunks they collected from the Afar. They showed that magmas actually came from quite deep–greater than 80 kilometers, or 45 miles, within the earth’s mantle–and formed under extraordinarily high temperatures, above 1,450 degrees C, or 2,600 F.
This implies that magmas are generated by a long-lasting plume of mantle heat. It also indicates that magma must make its way up through a surprisingly thick lid of solid rock, called the lithosphere. This idea has been supported by some seismic images of the Afar subsurface.
Rifting here is fairly slow—one or two centimeters a year, or 0.4 to 0.8 inches, and this may partly explain why so much solid rock persists. As the lithosphere is pulled apart, it does stretch, crack and thin. However, because the process in this region takes so long, the base of the lithosphere has time to cool down by losing heat to the colder rock above. This keeps the relatively cold, brittle lithosphere thicker than would be expected, and counteracts stretching. Sometimes, though, magma suddenly spurts long distances to the surface, and the earth visibly cracks and pulls apart during spectacular rifting events. That includes a series of events that started in 2005, and was closely observed by scientists.
Parts of the rift have already sunk below sea level. In the distant future–maybe 10 million years from now–the process will advance so far that the Red Sea will break through and flood the region. A new sea will open up, whether or not there is anyone around to name it.
In East Africa, earth’s crust is stretching and cracking, in a process called rifting. Here in the Afar region of northern Ethiopia, hundreds of faults and fissures have formed over time. (David Ferguson)
An important force driving the rifting is magma created beneath earth’s rocky outer shell, which has forced its way upward to push apart the crust. This eruption happened in the Afar in June 2009. (David Ferguson)
This crevice opened in a matter of hours, during a sequence of very large earthquakes in September 2005. It formed in response to magma being injected into the shallow crust, and is still emitting volcanic gases. This injection of magma was the largest event of its kind to be observed by scientists. (Lorraine Field)
Fresh lava erupted onto the desert floor preserves fragile surface textures, formed as the viscous molten rock cooled and hardened. Over time, these sharp features will erode away. (David Pyle)
A remote field site within the rift. Afar is one of the hottest and most sparsely populated regions on the planet. (David Pyle)
In a region that is vast, largely roadless and dominated by armed tribes, scientists depend on helicopters to get around, and on local people to act as guides and security guards. The climate necessitates large amounts of portable drinking water. (David Ferguson)
Lavas forming the rift surface cracked apart during an earthquake in 2005 to form this fault. The horizontal boundary between the light and dark area marks the pre-2005 ground surface, and shows that the area in the foreground dropped several meters during the quake. The geology of Afar provides many clues to the tectonic and magmatic process operating beneath our feet. (David Pyle)
All of us on the science team have had our turn being indoctrinated in the "perils" of XBT deployment. In this video, Luke demonstrates the proper technique for launching an XBT.
Prior to boarding the Langseth, my expectations of the food on board were clouded with visions of elementary school cafeteria slop doled out in aluminum trays and eaten with sporks and a side of plastic bag infused with milk. Little did I know that the folks on board take their food quite seriously. The three meals prepared each day are easily the most anticipated events of a crews’ day.
The galley (a.k.a. the kitchen in land dweller speak) is manned by a cook and steward who are responsible for sustaining the morale for the 53 people on board. The mess is regularly stocked with snacks like crackers, raisins, peanuts, dried prunes (yuck!), popcorn, cold cereal, microwave pasta, deli meats and cheeses, an assortment of milks and juices, coffee, tea, ice cream, and “fresh” fruits and vegetables (which will slowly be replaced with canned fruits and vegetables as the days go by). Cookies and pastries are also available at select times during the day if one is lucky enough to get there before they’ve all been consumed.
Lunch at the mess with Luke, Sarah, and Tyler.
We made it! According to the 30 minute log, which is one of the duties that we are given while on watch, we sustained up to 40 knot (74 km/hr, 46 mph) winds and ~7m (23 ft) seas for a few hours last night. That said, and aside from a relative lack of sleep, most of us seem to be no worse for wear. We also managed to travel north of our next sail line by almost an entire degree of latitude, which translates to ~111km (69 miles). We have now turned around, and are heading back to the survey area while working on streamer one. We will then re-deploy the air guns, and re-engage the survey in a couple of hours.
Same view taken this morning.
Spanish, English, and American motion sickness remedies.
My laptop's ready!
Poseidon's Zodiak on the way over to exchange supplies.
A few years ago, it was realised that seismic provides a method of directly observing the mixing processes, as the different water layers have sufficiently different seismic velocity and salinity for reflections to be generated at their boundaries: we have already seen reflections in the water column of our data, probably from boundaries between North Atlantic water and warmer, more saline Mediterranean water. However there have been relatively few studies of these processes using traditional oceanographic and seismic techniques, a deficiency being rectified by the deployment of XBTs at regular intervals during our cruise.
A successful exchange on medium-high seas!!
In addition to deploying ocean bottom seismometers to record our seismic shots, the German research vessel F.S. Poseidon has been carrying out oceanographic measurements, mainly using CTD casts (conductivity-temperature-depth), which provide more information than XBTs. As a result they had several XBTs left over. These they transferred to us this morning: Poseidon came within about 1 km of the Langseth and sent the XBTs over in a small boat. A real bumpy ride!
Goodbye, until we meet in Vigo!Tim Reston
University of Birmingham
Today the Poseidon is recovering eight OBH to download the data they recorded and redeploy them elsewhere within the 3-D box. It will be exciting to see the first OBH data! We won't see the rest of the data until the remaining OBS and OBH are recovered in August and September.
Despite being in the same area, here on the Langseth the science party hasn't seen the Poseidon since our first day passing them on the way out to sea from Vigo. However, this may be because we are all busy below deck in the main lab (with no windows) processing data!
Map in the main lab showing planned profiles. The ones we've already completed are in green
*Follow our progress on the "Survey Area" page as we update the sail lines every ~4 days.
Marine reflection seismology involves actively generating soundwaves (rather than waiting for earthquakes as in many other types of seismology). The ideal seismic source is as close to a “spike” as possible. Sound waves from the source travel into the Earth, where they reflect off sedimentary layers as well as hard-rock surfaces. The returning reflections are recorded by over a thousand hydrophones (underwater microphones that gauge pressure changes created by the reflected seismic waves) in the streamers that we have been deploying for the last four days.
The source consists of a series of air guns of varying sizes, which are hung at a depth of 9m (~30 feet) below large inflatable tubes. The tubes are 60m (~200 feet) long and each has 9 active air guns (10 with one to spare). In our case there are two sets of air guns being towed 150m (~500 feet) behind the ship, that alternately fire. To create a strong source that is as spike-like as possible, the guns are carefully arranged and fire almost simultaneously. The air is released from the chamber of the air gun, creating a 3300 cubic inch bubble pulse, which collapses to create the sound waves.
Orientation of the streamer and gun arrays being towed by R/V Langseth.
The red circles indicate the location of the gun arrays.