Deep Well Seismology at Parkfield, CA: Sensor Array and Microearthquake Wave VSP

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The United States Geological Survey is opening the 5030-ft-deep Varian A-1 well, 4 km southeast of the expected epicenter of the next Parkfield earthquake. It is proposed to NSF that this well be instrumented with a 4-part sensor array to conduct basic research into the character of small earthquakes and the physical properties of the San Andreas Fault Zone. The design, installation, data collection, and data analysis for this project will be conducted by University of California, Santa Barbarba in collaboration with University of California, Berkeley. The sensor array will consist of: (1) an "ultra low frequency" downhole pressure transducer and 1-hz seismometer at the bottom of the well, (2) a set of 8 "low frequency", 2-hz 3-component gimbled seismometer packages spaced at 200-meter intervals along the well, (3) a set of 8 "high frequency", 4.5-hz 3-component pressure-cased seismometer packages at 20-meter intervals near the bottom of the well, and (4) a set of 8 "ultra high frequency" 1000-hz 1-component accelerometers at 2-meter intervals, also near the bottom of the well. In this present proposal, UCSB seeks funds to construct and cement the array into the well. An additional but separate part of our proposal is to collect microearthquake data and analyze microearthquake Vertical Seismic Profiles recorded on the "low frequency" part of the array. Requests for funding of data collection and analysis for the other parts of the array will be submitted in separate proposals by UCB.