Introduction

In October and November 1998, the U.S. Geological Survey, Virginia Polytechnic Institute, Stanford University, and Geometrics Corporation jointly acquired a highresolution seismic reflection/refraction profile across the San Andreas Fault Zone (SAFZ) and the proposed San-Andreas-Fault-Observatory-at-Depth (SAFOD) drill site located near Parkfield, California (Fig. 1a). We refer to this seismic survey as the Parkfield Seismic Imaging-Ninety Eight (PSINE) survey, the highest-resolution seismic survey yet completed across the SAF in central California. This report, which presents acquisition parameters and example shot gathers for the PSINE seismic survey, is intended to provide necessary information for those who wish to use the PSINE data for research. The PSINE survey is part of the proposed SAFOD investigation: a proposed study to investigate physical and chemical properties and processes that control deformation and earthquake generation within the SAF zone by drilling into the active trace of the fault (Zoback et al., 1998; www.earthscope.org). Geological and geophysical investigations are planned prior to, during, and after completion of the borehole. The PSINE survey, which was one of the pre-drilling investigations, was designed to determine the subsurface stratigraphic and structural relations in the vicinity of the proposed drill site, to better locate the target fault zone within the subsurface, and to image obstacles that may impede drilling. Data acquisition parameters, experiment setup, and parameters needed to work with the PSINE data are provided in this report. The PSINE data provide useful reflective images (Catchings et al., in prep; Rymer et al., in prep; Hole et al.,) and velocity data (Catchings et al., 2002) in the vicinity of the SAFOD drill site and the San Andreas fault.