High-resolution seismic imaging data acquired in 2021 across a trace of the San Andreas Fault at Mee Ranch, Monterey County, California

In April of 2021, the U.S. Geological Survey conducted a high-resolution seismic survey at Mee Ranch in Monterey County, California. Both passive- and active-source seismic data were acquired using DTCC SmartSolo 3-component nodal seismograph systems ("nodes"), which continuously recorded data at rates up to 2000 samples per second. For passive-source acquisition, a 6x5 grid of nodes was deployed for several weeks before and during the active source shooting. For active-source acquisition, 395 nodes were deployed 1 meter apart (2 meters apart near the endpoints) along a southwest-northeast trend to create an approximately 500-m-long linear array. Additional nodes were deployed at 1 or 2 meter spacing along 25- and 50-m-long linear arrays centered about a known section of the fault. P-wave data were generated near each recording station of the main linear array using a Betsy seisgun firing an 8-gauge blank shotgun shell. P-wave data were also generated every 20 stations along the main linear array using approximately one/third pound of buried explosives. Fault-zone-guided-wave data were generated using explosive sources that were placed within a mapped trace of the San Andreas Fault zone and close to the shorter linear arrays. Finally, S-wave data were generated at each station using an aluminum block struck by a sledgehammer. Shot gathers were created in SEG-Y format (Barry et al, 1975) by extracting several seconds of data from each node for each recorded shot time. The passive grid data were converted to gain-corrected miniseed day files (Ahern and Dost, 2012). This report provides the metadata needed to analyze the seismic data. References: Ahern, T. and Dost, B., 2012, Standard for the Exchange of Earthquake Data (SEED) Manual: International Federation of Digital Seismograph Networks Incorporated Research Institutions for Seismolog, version, 2.4. Barry, K.M., Cavers, D.A., and Kneale, C.W., 1975, Recommended standards for digital tape formats: Geophysics, vol. 40, no.2, p.344-352.