HR: 14:40h
AN: G32B-05    [PDF]
TI: Broadband Deformation in the San Francisco Bay Area\\ Measured at Mini-PBO Stations: Implications for PBO
AU: * Murray, M H
EM: mhmurray@seismo.berkeley.edu
AF: Berkeley Seismological Laboratory, 215 McCone Hall, Univ. of California, Berkeley, CA 94720-4760
AU: Johnston, M J
EM: mal@usgs.gov
AF: U.S. Geological Survey, 345 Middlefield Rd., Menlo Park, CA 94025
AU: Linde, A
EM: linde@dtm.ciw.edu
AF: DTM, Carnegie Instit. of Washington, Washington, DC 20015
AU: Roeloffs, E A
EM: evelynr@usgs.gov
AF: CVO, U.S. Geological Survey, Vancouver, WA 98683
AU: Agnew, D C
EM: dagnew@ucsd.edu
AF: IGPP, University of California, La Jolla, CA 92093
AU: Rousset, S
EM: rousset@seismo.berkeley.edu
AF: Berkeley Seismological Laboratory, 215 McCone Hall, Univ. of California, Berkeley, CA 94720-4760
AU: B\"urgmann, R
EM: burgmann@seismo.berkeley.edu
AF: Berkeley Seismological Laboratory, 215 McCone Hall, Univ. of California, Berkeley, CA 94720-4760
AU: Romanowicz, B
EM: barbara@seismo.berkeley.edu
AF: Berkeley Seismological Laboratory, 215 McCone Hall, Univ. of California, Berkeley, CA 94720-4760
AU: Sacks, S I
EM: sacks@dtm.ciw.edu
AF: DTM, Carnegie Instit. of Washington, Washington, DC 20015
AU: Silver, P G
EM: silver@dtm.ciw.edu
AF: DTM, Carnegie Instit. of Washington, Washington, DC 20015
AB: We report on 5 borehole stations installed in the San Francisco Bay area with strainmeters, seismometers, pore pressure monitors, tilt sensors, GPS, and high-frequency 24-bit recording systems. These ``Mini-PBO" stations are part of an NSF-funded project to develop a pilot system for the study of transient plate boundary deformation from fractions of seconds to years in central California. We are currently resolving interaction problems, such as electical grounding, that are typically encountered during the hookup of such complex systems, and are in the initial stages of assessing the data quality of the instrumentation. The tensor strainmeters use the CIW hydraulic system to measure the volume change in 3 sensing volumes that form 120-degree sectors of an annulus, allowing the 3-component horizontal strain tensor to be determined. The tensor strainmeters, pore pressure monitors, and tiltmeters appear to reliably measure tidal strain, and local and teleseismic earthquake deformation. We will present studies of noise spectra and tidal calibration to better assess the performance of the strainmeters. We plan to add pre-amplifiers to the 3-component 2-Hz velocity borehole seismic packages to improve the signal at some of the stations where the microseismic noise peak around 0.1 Hz currently is not evident. The GPS antennas are mounted at the top of the borehole casings in an experimental approach to achieve inexpensive yet stable monuments. We will present noise studies that compare their stability with more conventional monuments. The lessons learned from the analysis and integration of the different data types produced by the Mini-PBO project should pave the way for users of the more extensive data sets that will be acquired through the dense instrumentation deployments planned under PBO.
DE: 1206 Crustal movements--interplate (8155)
DE: 1294 Instruments and techniques
DE: 8107 Continental neotectonics
SC: Geodesy [G]
MN: 2003 Fall Meeting