At the end of May, Emilie Hooft, an Earth Sciences Professor at the University of Oregon, invited me to help with a large-scale deployment of seismic sensor nodes. I was part of a team of about 30 undergrad and grad students, along with four professors, who during the course of two weeks traveled into the Coastal Range of southwestern Washington and western Oregon to place these nodes at pre-planned positions. We placed approximately 750 sensors. In my discussion with professors and students directly involved in the research, I learned that this was perhaps one of the largest seismic studies every conducted in terms of scale and density.
The sensors were left in the field for nearly a month, during which time a ship operating off the coast used an air hammer to generate signals that were reflected off the subduction zone to the sensors. Additionally, the ship also deployed ocean bottom sensors. At the end of the marine operations, most of the team returned to recover the sensors. Presently, those involved with the study are awaiting for the data to be retrieved from the sensors so that they can begin their analysis. Since my research projects are in a different area, I will not be involved with this effort.
These sensors were fairly easy to place. We dug holes sufficiently deep to cover the sensor with a couple inches of ground, placed the sensor, oriented the axis to true north, leveled the top surface of the sensor, then covered the sensor. Additionally, we recorded a GPS way point and placed a visible tag near the burial location. The big effort was the hours of driving and navigating forestry roads to the pre-planned sites. Many of our students received their first experience of driving and maneuvering heavy-duty 4×4 vehicles in narrow, rugged roads. Thankfully, we had no major accidents; however, one of our team learned how to change a flat tire in the back country.
So why this project? There is a growing expectation in the earth science community that a large magnitude earthquake will be generated by plate and fault movements in the subduction zone. The data from this study is hoped to be of sufficient resolution for geophysicists to update models to improve early warning apparatus. There are also the typical and numerous scientific motivations that attend efforts of this scale. Poignantly, during the deployment phase, I recall hearing news reports for three separate earthquake events: two in the Pacific Ocean off the southern coast of Oregon, and one at Mount Hood. I sincerely hope the principal investigators will realize all of the goals they set out to accomplish.
