This project covers WHOI's participation in the Ocean Bottom Seismic Instrument Pool for four years. WHOI currently operates two different types of ocean-bottom seismometers for the Pool: 50 short-period instruments optimized for both active-source experiments and passive microseismicity monitoring, and 25 broadband seismometers optimized for teleseismic structural studies and earthquake-source investigations.
The goal of this project was to provide state-of-the-art ocean-bottom seismographs (OBS) and complete at-sea technical assistance for the collection of marine seismic data by the U.S. scientific community. In addition, all data recorded by this instrumentation were to be archived in standard formats at the Incorporated Research Institutions for Seismology (IRIS) Data Management Center (DMC). The Ocean Bottom Seismology Group at WHOI operates 4 different typs of OBS, all of WHOI design: a small, compact, short-period OBS, nicknamed "D2", optimized for both active-source experiments and passive microseismicity monitoring, a larger, broadband seismograph, BBOBS, optimized for teleseismic structural studies and earthquake-source investigations; a combined broadband/strong-motion OBS built with funding from the Keck Foundation; and an intermediate-period OBS built using ARRA funds. Although distinct instruments, these systems have many common components, viz. data logger, clock, acoustic release, and recovery board. The current WHOI OBS inventory consists of 30 "D2" short-period OBS, 30 broadband OBS, 18 ARRA-funded intermediate-period OBS, and 10 Keck-funded OBS. Over the lifetime of this award (but not including experiments funded via the IRIS OBSIP Management Office), the WHOI OBSIP group has supported 14 NSF funded experiments for 38 unique P.I.s. These experiments required 32 unique cruises. The total number of successful OBS deployments/recoveries is 425, for a combined 216 years of on-bottom recording. All of the broadband and short-period data have been archived at the IRIS DMC in SEED format. The archived data includes all metadata. In addition, active-source data have been archived at the IRIS DMC in SEGY format. The experiments supported by the WHOI group include both earth structure and earthquake source studies. Structural experiments have used natural and artifical sources to image the mantle beneath oceanic hot-spots, and the crust and mantle beneath mid-ocean ridges, subduction zones, and rifted continental margins. Earthquake experiments have mapped seismicity, and variations in earthquake rupture properties at oceanic transforms.
