HR: 09:30h
AN: S41C-06    [Abstracts]
TI: A Pilot Experiment in Collaborative Science and Engineering
AU: * Steidl, J H
EM: steidl@crustal.ucsb.edu
AF: Institute for Crustal Studies, University of California at Santa Barbara, Santa Barbara, CA 93106 United States
AU: Working Group, G
EM: gomberg@usgs.gov
AF: Institute for Crustal Studies, University of California at Santa Barbara, Santa Barbara, CA 93106 United States
AB: We report on a pilot field experiment, meant to demonstrate the value of combining resources from multiple earthquake science and engineering facilities. Our initial intent was to employ a mobile shaker truck from the Network for Earthquake Engineering Simulation (NEES) facility with US Geological Survey (USGS) and Incorporated Research Institutions for Seismology (IRIS) seismographic instrumentation in a single study. The final experiment grew into four studies with additional participation from the Los Alamos National Lab and other NSF-sponsored consortia; the MAEC, SCEC, CENS, and HPWREN. The field experiment piggybacked on an earlier planned inaugural demonstration of NEES facilities, held at the NEES Garner Valley Digital Array (GVDA) site in southern California. We recorded ground motions generated by the `TRex' shaker truck at the GVDA and surrounding Garner Valley during August 18-22, 2004 and will continue to collect earthquake data for several months. Our first study tests the potential for generating and measuring nonlinear sediment response by recording TRex strong shaking on a temporary surface accelerometer micro-array and permanent GVDA down-hole accelerometers. Our second study focuses on ground motion site and basin effects by recording TRex signals at 20 temporary real-time, telemetered seismic stations deployed from the center to the edge of the basin. Earthquake signals recorded on this basin array will allow us to validate the process of extrapolating results from the artificial, surface source to those from natural earthquakes. The relatively small scale of the Garner Valley basin (4 km by 10 km, sediment depths less than 25 m) makes its characterization feasible, but scalable to larger basins elsewhere and motivates our third study in which we conduct a variety of imaging experiments. Basin array data will constrain broad-scale shear and compressional wave tomographic images of the basin structure. To constrain a higher-resolution image along a profile across the basin, we also collected reflection data generated by TRex recorded on densely spaced geophone strings, and conducted a sledge-hammer survey at even higher resolution to confirm the location of a suspected buried fault. For the fourth study, we assess the potential for shakers like TRex to do broad-scale, deep imaging as we stack TRex signals emitted repeatedly for nearly an hour, recorded on stations of the regional ANZA and statewide California Integrated Seismic Networks.
DE: 7223 Seismic hazard assessment and prediction
DE: 7299 General or miscellaneous
DE: 7212 Earthquake ground motions and engineering
SC: Seismology [S]
MN: 2004 AGU Fall Meeting