Fieldwork in Bangladesh during the end of Ramadan and Eid festival
I’m on the campus of Bangladesh Open University (BOU) in Bangladesh with Eid al-Fitr celebrations later this morning. Last evening the month of Ramadan, when Muslims quick during sunlight hours got here to an end. Our group was on the manner again from the area at sundown when Ramadan ended and the Eid festival started. We stopped at a restaurant in Gazipur and had massive plates of biryani. Those in our group who’re fasting had not eaten since 3:30 am this morning.
Arman breaks his Ramadan quick with mutton biryani to start out the Eid.
I’ve returned to Bangladesh as soon as once more. I’m taking benefit of the magnetotelluric (MT) devices that had been shipped right here for my final journey to gather extra electromagnetic information in northeast Bangladesh earlier than they should be returned to the U.S. In addition to the 4 broadband (BB) devices that we used in March, Samer Naif from Georgia Tech, is bringing 4 long-period (LP) ones that may see even deeper. This time, we’re deploying the devices for 3 (BB) to six (LP) days at a time. The longer deployments can higher decide decrease frequency indicators that may see deeper into the earth. With the BB, we count on to see the whole 15-25 km of sediments right here. With the LP, we’ll see 30-40 km to the Moho, the backside of the crust.
Arman and Biplab dig a gap for the vertical magnetometer with a submit gap digger in a just lately harvested rice area.
We are doing this experiment in an element of Bangladesh that’s tectonically lively. The identical fault that ruptured in the 2004 Sumatra earthquake continues into Bangladesh, however is buried by the thick sediments right here. We need to picture the fault, the subduction megathrust, inside the sediments, and the bending of the crust as the Indian plate is subducted beneath the IndoBurma subduction zone. Both are poorly recognized, however impression our evaluation of the earthquake hazard right here.
An area farmer helps dig the trench for the north-south magnetometer utilizing a kodal.
Fieldwork during May, the hottest and most humid month earlier than the monsoon rains begin in June will not be very best. Neither is making an attempt to work via the end of Ramadan and the largest vacation of the 12 months. However, we’re restricted by the must return the BB MT devices and the cropping season. We are attempting to work between the harvesting of the spring rice crop and the planting of the summer season crop since our devices should be buried in the fields over a 100 m by 100 m space.
Masud helps Samer together with his two carts full of gear at the Dhaka airport.
Our plans in Bangladesh at all times should be versatile, this time from the very begin. Samer missed his flight from the U.S. making an attempt to cope with journey paperwork and the 7 items of baggage containing the LP MT devices. Oliver, his pupil, and I arrived on time on the morning of April twenty ninth and had been met at the airport by Masud, Arman and Biplab, three Dhaka University college students who had been with me on the final journey, and thus are accustomed to putting in MT devices. However, as a substitute of a ship, we’re touring by vans pushed by Babu, our long-term driver and Sumon. We all continued from the airport north to the important BOU campus, the place my long-term collaborator, Humayun Akhter is now the Vice-Chancellor. The BB MT had been saved right here. We spent our first afternoon retrieving the devices and getting arrange in the BOU guesthouse, the place we will probably be staying.
Arman, Biplab, Samer and Oliver stand by the folding cart that we introduced for transporting the gear.
We will deploy the devices in a 200 km lengthy transect from right here to the jap edge of Bangladesh throughout the subduction zone and the many folds and faults that deform the sediments. We may even do a shorter north-south transect to seize the northward tilt of the deformation. Once the devices are put in, we plan to shift 1-2 of them every day for many of a month. Since the LP MT are at every website longer, and should return to the U.S. when Samer leaves, we could have many fewer of these stations. Our plan to start out putting in the LP MT immediately was foiled by Samer lacking the aircraft.
Samer establishing one of the LP MT devices to file the information.
The MT devices embrace electrodes that have to be positioned ~50 m from the recorder in every of the cardinal instructions to measure the electrical area. The BB MT have 3 magnetometers that have to be buried dealing with north, east and vertical. Burying the 1 m lengthy coils are the hardest half of the deployment in the warmth. The LP devices has a smaller magnetometer that measures all 3 parts, however have to be fastidiously oriented in its gap. They are each powered by massive automobile batteries – 1 for the LP and 3 for the BB.
Two farmers chopping a ripe area of rice.
To set up the MT with out disturbing crops, we’d like locations the place the rice has been harvested, a minimum of for the central recorder and the magnetometers. Having a tough spatial association for the array in mine, we choose promising websites from Google Earth photographs of the fields and Chris Small processing of satellite tv for pc information to point out vegetation, water and soil. Unfortunately cloud cowl obscured current photographs for the first half of our deployment, so we’ve got been flying blind.
A gaggle photograph of the 6 of us with native farmers and youngsters.
To keep away from the warmth and accommodate Ramadan, we’re working early. Those observing have breakfast at 3:30 am earlier than morning prayers and a nap. The relaxation of us have breakfast at 5:30 am. We then all meet at 6am to pack for the day and head off to the area. The morning after we arrived, we set off for our goal space and scanned the fields alongside the manner. On our first attempt, we bought fortunate. We spied a promising space from the important street, then took native roads to get as shut as doable. We hiked into the fields and discovered some fields that had just lately been harvested. An area farmer directed us to the proprietor, and we some we had been deploying. We employed the different farmer to guard the devices.
A market the place native produce, each acquainted and unfamiliar, is being bought.
We completed out first website, simply in time for Masud and I to go to the airport to get Samer. Since he bought via customs shortly, we had been capable of set up an LP MT in the afternoon. For that website, we tried a area that we had noticed on the option to the earlier website and had comparable success. On that first afternoon, the temperature was 94°, however the humidity made it really feel like 110°. Despite the issues and the warmth, it was first day of fieldwork.
Samer makes use of a laser rangefinder for distance whereas Oliver friends via a hand-bearing compass for route to place one of the electrodes.
The subsequent day additionally went effectively. For one, the preliminary attempt was no good as a result of of close by energy traces, however we had been capable of finding a wonderful place on the second attempt. There was a harvested area in the center of a bigger set of fields. We may put the recorder, battery and magnetometer there, whereas the electrodes prolonged into the nonetheless maturing rice round it. For the second website, we drove down an area street then tried a barely satisfactory street so far as we may go. It was far sufficient for us to stroll to the open fields. In the end we succeeded in placing in two extra LP websites.
Masud fingers out candies to the native youngsters after finishing one other MT website.
Our third day, the final of Ramadan, began off effectively. In our goal space we drove alongside the solely native street vast sufficient for our van. It didn’t go the place I hoped, nevertheless it did lead us to website after ~2 km of driving. Then our good luck ran out. For the second website, we discovered a doable area, however the farmer didn’t give permission. Samer and Arman went to restore a cable that an animal have bitten trough, whereas the relaxation of us saved trying. Four extra tries later we gave up. This space was simply too densely populated, and the few potential websites had high-voltage energy traces throughout them. We determine to place in an additional website farther east and went to scout there. Samer and Arman mounted the drawback and in addition they couted one other website. We met up and drove again, breaking the Ramadan quick alongside the manner. The scouting signifies that we should always be capable to set up two websites tomorrow, as a substitute of the one we anticipated resulting from the vacation.
Samer walks via a area of ripening rice after checking the instrument recordings.
Masud walks by a jackfruit tree. The massive fruit will probably be able to eat later this month.