High-resolution seismic imaging of the West Napa Fault Zone at Buhman Avenue, Napa, California

In November 2016, the U.S. Geological Survey acquired high-resolution P- and S-wave seismic data across the surface trace of the West Napa Fault zone near Buhman Avenue in Napa, California. We acquired seismic reflection, refraction, and guided-wave data along a 117-m-long profile across the known surface rupture zone of the West Napa Fault zone. To acquire the reflection and refraction data, we co-located shots and geophones, spaced every meter along the profile. We used 118 SercelTM L40A P-wave (40-Hz vertical-component) geophones with a sensitivity of 22.34 volts/meter/second to record 118 P-wave shots. We also used 118 SercelTM L28-LBH S-wave (4.5-Hz horizontal-component) geophones with a sensitivity of 31.3 volts/meter/second to record 118 S-wave shots. We generated P-wave data using a 2.5-kg sledgehammer and steel plate combination. S-wave sources were generated by horizontally striking an aluminum block with a 2.5-kg sledgehammer. We acquired fault-zone guided-wave data by generating P- and S-wave energy (2.5-kg sledgehammer and steel plate or aluminum block) approximately 44 and 55 m northwest of the P- and S-wave recording arrays. All data were recorded using two 60-channel Geometrics Stratavisor NX-60TM seismographs with a 24-bit analog-to-digital converter (Subcommittee of the SEG Engineering and Groundwater Geophysics Committee, 1990); the seismographs were connected to the P- and S-wave geophones via refraction cables. Each shot was recorded for two seconds, with data recording starting 100 ms before the actual time of the shot. Data were recorded at a sampling rate of 0.5 ms, or 2000 samples per second. This report provides the metadata needed to utilize the seismic data.