HR: 1330h
AN: S52D-0162    [PDF]
TI: MOBB: Data Analysis from an Ocean Floor Broadband Seismic Observatory
AU: * Uhrhammer, R A
EM: bob@seismo.berkeley.edu
AF: Berkeley Seismological Laboratory, 215 McCone Hall #4760, Berkeley, CA 94706 United States
AU: Dolenc, D
EM: dolenc@seismo.berkeley./edu
AF: Berkeley Seismological Laboratory, 215 McCone Hall #4760, Berkeley, CA 94706 United States
AU: Romanowicz, B
EM: barbara@seismo.berkeley.edu
AF: Berkeley Seismological Laboratory, 215 McCone Hall #4760, Berkeley, CA 94706 United States
AU: Stakes, D
EM: debra@mbari.org
AF: Monterey Bay Aquarium Research Institute, 7700 Sandholdt Rd., Moss Landing, CA 95039 United States
AU: McGill, P
EM: mcgill@mbari.org
AF: Monterey Bay Aquarium Research Institute, 7700 Sandholdt Rd., Moss Landing, CA 95039 United States
AU: Neuhauser, D
EM: doug@seismo.berkeley.edu
AF: Berkeley Seismological Laboratory, 215 McCone Hall #4760, Berkeley, CA 94706 United States
AU: Ramirez, T
EM: tony@mbari.org
AF: Monterey Bay Aquarium Research Institute, 7700 Sandholdt Rd., Moss Landing, CA 95039 United States
AB: MOBB (Monterey bay Ocean floor Broad Band project) is a collaborative project between the Monterey Bay Aquarium Research Institute (MBARI) and the Berkeley Seismological Laboratory (BSL). Its goal is to install and operate a permanent seafloor broadband station as a first step towards extending the on-shore broadband seismic network in northern California, to the seaside of the North-America/Pacific plate boundary, providing improved azimuthal coverage for regional earthquake and structure studies. The MOBB station was installed on the seafloor in Monterey Bay, 40 km offshore, and at a depth of 1000m from the sea surface, in April 2002, and is completely buried under the seafloor level. The installation made use of MBARI's Point Lobos ship and ROV Ventana and the station currently records data autonomously. Dives are scheduled regularly (about every three months) to recover and replace the recording and battery packages. Some data were lost in the first half of 2003 due to hardware and software problems in the recording system. The ocean-bottom MOBB station currently comprises a three-component seismometer package (Guralp CMG-1T), a current-meter, a digital pressure gauge (DPG), and recording and battery packages. The seismometer package is mounted on a cylindrical titanium pressure vessel 54cm in height and 41 cm in diameter, custom built by the MBARI team and outfitted for underwater connection. Since the background noise in the near-shore ocean floor environment is high in the band pass of interest, for the study of regional and teleseismic signals, an important focus of this project is to develop methods to a posteriori increase signal to noise ratios, by deconvolving contributions from various sources of noise. We present results involving analysis of correlation of background noise with tide, ocean current and pressure records, combining data from MOBB and regional land based stations of the Berkeley Digital Seismic Network (BDSN). We also present preliminary results of modeling of the signal generated noise due to reverberation in the near surface sedimentary pile. The experience gained in MOBB will be valuable, in particular, for future long term or temporary deployments of buried broad-band seismometers such as are envisaged in the context of the Ocean Mantle Dynamics Initiative.
DE: 7203 Body wave propagation
DE: 7205 Continental crust (1242)
DE: 7260 Theory and modeling
DE: 7294 Instruments and techniques
SC: Seismology [S]
MN: 2003 Fall Meeting