``````Duke Participation in SAFOD: Two Collaborative Seismic Profiling Studies using the Geophone Array in the SAFOD Pilot Hole

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`We propose a seismic-while-drilling (SWD) study of the San Andreas Fault Zone using the geophone array in SAFOD Pilot Hole. The study adds the downhole components to the currently-funded surface-seismic profiling and drilling projects at the SAFOD site. The scientific objectives of the SWD study are to: (1) establish the subvertical fault structure and material properties of the SAFOD site and (2) begin the time-lapse monitoring of these structures and properties. In the field portion of our study, we will collect data with the Pilot Hole geophones. The purpose of this study is to determine the subsurface rock properties adjacent to and within the San Andreas Fault and in monitor their time dependent changes. In particular we are seeking to determine the bulk properties of the materials surrounding the source zones of SAF microearthquakes. We will examine all the SWD data we collect for wave propagation effects such as anisotropy, attenuation, and complex reflection and refraction effects. By utilizing the seismically quiet downhole environment of the Pilot Hole geophone array, we will also be establishing a high-resolution baseline data set for future "time-lapse" geophysical monitoring of the SAFZ. Such data are used to follow the rock-fluid-stress evolution of energy reservoirs, a procedure we wish to eventually apply at the SAFOD site.