University of Miami shallow buried OBS experiments at the Oregon Margin.

Abstract

A new method of OBS burial has been successfully tested in 3000-m-deep waters of the Oregon Margin during the cruise on board R/V Wecoma in September 1991. Guralp CME-3 broadband seismometers were buried approximately 1 m below seafloor. Approximately 50 h each of continuous data were successfully collected at OM-1 (44 42.5’ N, 125 32.3’ W) and OM-8 (45 04.83’ N, 125 24.96’ W) sites. A local earthquake event at 01:36 a.m., 12 September (Oregon time) was clearly recorded in the seismic channels and pressure channel at OM-1 station. The time-averaged frequency spectra of vertical acceleration and pressure show a quiet notch at 0.04 to 0.10 Hz as well as very high coherency between channels both at the infragravity wave band (0.003 to 0.03 Hz) and at the double frequency microseism band (0.10 to 0.50 Hz). The crustal structures of compressional wave velocity, shear wave velocity, and porosity down to 10 km below seafloor are determined at a resolution of a few hundred meters using BSMP inversion of the infragravity data. [Work supported by NSF.]