We have aced AACSE – last blog!

I have been traveling to Alaska for earthquakes since 1990. I have helped lead a half dozen major data-collection projects and helped deployed about 230 earthquake seismometers throughout the state. Of all of these projects, nothing has been as large in scope or as complex as the Alaska Amphibious Community Seismic Experiment – AACSE. I drew the short straw when AACSE was being planned, and wound up coordinating much of the behind-the-scenes logistics, everything from scheduling ships to finding bear-resistant boxes. By “coordinating” of course, I mean other people did all the work.  There is a huge list of names I should thank, and will completely fail to do so, I would just emphasize that the project is very much a team effort.

We have just completed the last OBS recovery leg. As we are preparing to disembark from the ship, I am a bit stunned at how successful this all is – we wound up fantastic quality and volume of data, with more kinds of observations and more participation than ever expected. And the science is just beginning – the “Community” in AACSE is shorthand for saying that all the data are being made freely available to anybody, as fast as we can get it into repositories.

MGL1907_09-11-2019Our cruise track for the final OBS recovery leg and multibeam survey – Aleutian Trench is purple. We are trying to figure out what this shape resembles.

We have just finished the last recovery cruise and the R/V Marcus G Langseth, operated by Columbia University’s Lamont-Doherty Earth Observatory.  At about 4am on Sept. 10, when my shift started, we pulled the last ocean-bottom seismometer out of the water. At this point, we were done with years of work!

blogP1_WD54_recoveredLast OBS being fished out of the water (Photo G. Abers)

This has been a fabulously successful cruise, and tremendous fun. It is my first time as chief scientist on a large oceanographic ship, and it could have been very stressful. But in the end, it was great fun and very exciting due to a ton of people on board being fully committed to our success.  Thanks to everyone on the Langseth – the crew, the LDEO science tech staff, the WHOI OBS team, the Apply-to-Sailors who have been blogging, and the USGS experts aboard.

GroupPhotoThe science party for MGL1907 – the last AACSE OBS recovery and multibeam cruise on the Marcus G. Langseth.  We are in the Main Lab, the science nerve center of the ship.

The ship crew and science support staff makes this all easy, helping solve and anticipate any problems and providing all the information we need to make decisions – anything from how the ship is operating to the weather. The main event has been OBS recovery, in the hands of an incredibly talented team from WHOI who has done an excellent job of training our Apply-to-sail participants in every aspect of the process. It has been great to see how engaged and excited about data they have been. Our secondary objective has been to greatly enhance the bathymetric map off Alaska – thanks to the Langseth crew and our multibeam expert Bill Danforth from the USGS, we have added tons of new data across the trench that show faults, volcanoes, and submarine channels galore. This leads to a somewhat odd ship track, that looks like a badly-designed submarine or particularly unusual fossil fish (the first image in this blog shows where we have mapped).

All of this has gotten me to reflect on the entirety of the project, which really started seriously in 2016 when the PI team formed.  A good deal has happened!  Here, for example, is a photo I took of the seismometers in the LDEO OBS lab, being prepared for deployment in early 2018.

LDEO_OBS_prep_feb18Ocean Bottom Seismometer Lab at Lamont-Doherty Earth Observatory, showing some of the 45 OBSs they prepared for the AACSE deployment, early 2018.

Stepping back: one way to look at the scope of AACSE is by its statistics. We deployed 105 broadband seismometers, each sampling multiple components of ground motion 430 days, 100 times a second, in several components of ground motion. This adds up to about 3 Tb of seismic data. To collect it we sailed 12,070 nautical miles on research ships (more than half way around the planet), and flew something like 75 flight hours on small planes.  We took 14 field expeditions involving 73 plane tickets to Alaska (not counting ship and OBS personnel) – five major cruises, four land-station visits each involving two field parties, a siting trip and a short course. Of these trips, about 40 were for students through Apply-to-sail program, the undergraduate short course or other graduate students helping with the field work.  More prosaically, my calendar shows 150 conference calls and meetings related to this project over the last three years, and my email in-box for this project has 3656 messages – and I am sure many were missed. It all is extremely rewarding but not something to be undertaken lightly.

There are far too many people to thank personally, so I unfortunately have to do this by category: 10 other PIs (Aubreya Doug Emily Lindsay Susan Anne Donna Spahr Peter Patrick), another half-dozen core participants who have been involved in supplementary projects and field work, the 40 students and post-docs who all contributed more than they know, the staff of the WHOI and LDEO OBS labs  & the PASSCAL Instrument Center who made sure we got lots of excellent data, the support offices for the R/V Sikuliaq at UAF, the R/V Marcus G Langseth at LDEO, JASON at WHOI, the Alaska Volcano Observatory and Alaska Earthquake Center, many people in Alaska who have helped with permitting on federal, state, borough, private native-corporation lands, small-plane transport operators, shippers, local and national educators, reporters, the GeoPRISMS office, and others I am sure that I am forgetting. A special thanks goes out to the several program managers at the National Science Foundation who, once this was funded, did an incredible amount to support this complex project. And, going forward, to everybody who will find this data valuable and use it!

That’s it, we are done with this blog – what started as a simple activity to document life in the field has become something very memorable. We are looking into ways to merge and bind all these posts into a single sharable document. Regardless, we have oodles of data to keep us busy for years!

LastSunrise11sep19.jpg

The final sunrise off the R/V Langseth, heading back to Kodiak.

 

Geoff Abers, Cornell University

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