OBSIP Instrumentation and Operations for the Cascadia Initiative

Abstract:

The Ocean Bottom Seismograph Instrument Pool (OBSIP) is providing instrumentation and operations support for the Cascadia Initiative (Cascadia), an

American Recovery and Reinvestment Act funded community experiment focused on investigating the unique geophysical processes through a combined onshore and offshore array of seismometers. Currently, OBSIP has deployed and recovered the instruments for years 1, 2, and 3 of the experiment. Year 4 instrumentation is currently collecting data on the ocean floor until fall 2015.

Three OBSIP Institutional Instrument Contributors (IIC’s) designed and built 60 new Ocean Bottom Seismometers (OBSs) specifically for the unique requirements of the Cascadia region, including shallow water deployments and heavy fishing activity. Lamont-Doherty Earth Observatory (LDEO) and Scripps Institute of Oceanography (SIO) both designed new trawl-resistant frames for the OBS instruments. Woods Hole Oceanographic Institute (WHOI) built 15 new deep-water instruments. To aid in the recovery of the heavy trawl resistant enclosures, OBSIP uses a Remotely Operated Vehicle (ROV). Cascadia OBS instruments include a seismometer, either a differential pressure gauge (DPG) or an absolute pressure sensor (APG), and extensive supporting electronics.

One of the goals of the Cascadia Initiative is to encourage the joint use of onshore and offshore data. To support this goal, OBSIP has assembled a Horizontal Orientations report and an ARRA white paper summarizing the Cascadia Initiative performance. In both of these reports, OBSIP investigated the noise characteristics of the Cascadia OBS stations and the overall performance. With new instrumentation packages, the Cascadia instruments can be deployed in shallow water. OBSIP has investigated instrument performance to determine if water depth, instrument shielding, and recording season influence data quality.