Most research vessels have small gyms where people onboard can get a little exercise while at sea. A nice thing about the gym on the R/V Langseth is that it is well above the water line and has some windows, so you can look out at the sea while you log some miles on the treadmill or elliptical. To maximize social distancing, the stationary bike and weights have been moved out of the gym and into clear plastic enclosures built on the deck, so good views can now be had while cycling and pumping iron, too.
On Wednesday, I went for my first treadmill run. While trotting along – and trying not to fall off the treadmill as the boat pitched in response to broad, gentle swells – I saw a whale blow in the distance! We’ve been treated to regular whale sightings on our trip west.
The Aleutian arc is an active string of volcanoes formed over a subduction zone, where two of Earth’s tectonic plates collide and one is forced under the other. These geological settings create the largest and most destructive earthquakes and tsunamis and some of the most active volcanoes on the planet. While some of the magma generated at subduction zones erupts at arc volcanoes, a large portion of it crystallizes before reaching the surface, adding as much as 10-20 km to the crust, the outer layer of the Earth. Although subduction zones may be one of the most significant places where new continental mass is created, we still have many questions about the composition and thickness of this new material. The composition of lavas at the surface change dramatically between adjacent volcanoes – what is happening under the hood to create that variability?
The Aleutian subduction zone has also produced a series of very large earthquakes and tsunamis in the last century, including a magnitude 8.6 earthquake that occurred in our study area in 1957. Our imaging will provide new information on the source region of these earthquakes.
During this study, we will use sound waves to image the Aleutian subduction zone, with a focus on mapping the geology below the Aleutian volcanoes to determine the composition and thickness of the crust and how it varies along the arc under volcanoes with different lava compositions. Sound waves will be generated by a seismic sound source towed behind the ship, and returning sound waves will be recorded on ocean bottom seismometers deployed on the seafloor and a long cable filled with pressure sensors towed behind the ship; these are very sensitive instruments that can record weak returning sound waves from deep in the earth. Data will be collected on transects along and across the subduction zone. Additionally, we will be collecting a suite of other oceanographic and geophysical data throughout the cruise. We are excited about what we will learn – stay tuned!
A part of the marine science gig has always been spending weeks or even months away from home in isolated environments, but COVID-19 has added a new twist. To ensure that no one boarding the ship has the coronavirus, each of us had to quarantine at least 2 weeks in a hotel room in port before joining the ship and receive daily healthy checks and a couple of COVID tests.
Due to unanticipated delays, the twenty-two of us in Ketchikan have actually been quarantining for 3 weeks, and other members of our shipboard team quarantined even longer in Newport, Oregon. We have been allowed to go outside each day for socially distanced exercise, but otherwise we have stayed in our hotel rooms. All of our meals are left outside of our rooms. Serving sizes were generous….
I surveyed our group on how they passed the time during this long quarantine. Getting out for hikes helped many of us stay sane. Ketchikan is a cute town surrounded by rugged mountains covered in a temperate rain forest, so we were treated to great views, a few bear sightings, and frequent rain. A couple of us tried to learn new skills, from using Excel to playing mandolin. Others binged on the national political conventions and/or Shark Week (similar???). We made phone calls and video calls to loved ones; one person video-called a friend at dinner time each day to have company while eating, but had to call from the bathroom to get a good internet connection! And we did some work.
One way or another, we all made it through and will finally depart Ketchikan tomorrow on the R/V Langseth, and start our westward journey to the Aleutians. We are very grateful to everyone for undertaking this quarantine (and the associated hardship of being away from home even longer) and to everyone at the Lamont-Doherty Earth Observatory Marine Office, Ocean Bottom Seismic Instrument Center (OBSIC), NSF, and many others who have been working hard to make this expedition possible!