Now that we have finally arrived in our field area, we have spent the last two days steaming along a ~300-mile-long stretch of the Aleutian island chain between Seguam and Gareloi islands and deploying ocean bottom seismometers (OBS) from Woods Hole Oceanographic Institution and Scripps Institution of Oceanography on our first transect (see this post for a map). Our hard-working OBS teams ‘install’ them by lowering them over the starboard side of the ship with a crane and releasing them into the ocean. Because they have a weight attached to the base, they sink to the seafloor. The engineering that goes into ocean bottom seismometers is amazing. Each OBS is equipped with very sensitive instruments that can detect tiny ground motions and changes in water pressure, which they record on an internal computer. They can withstand high pressures at deep water depths. We can send the OBS basic commands using acoustic signals . They will stay on the seafloor for the next few days, and record sounds emitted from our seismic source array. Afterwards, we will pick them up – more soon on all of that!
The last two days of work has also allowed us to get a first look at our field area, especially the volcanoes that are the focus of our project. They are spectacular! Snow-capped mountains with a green fuzz of vegetation rise out of the ocean. They are lined by impressive sea cliffs and the occasional water fall. Amazing! I’m glad that we will get several more looks at them in the coming days as we steam up and down this transect collecting data and recovering instruments.
Donna Shillington NAU
