High-resolution seismic data acquired at six Southern California Seismic Network (SCSN) recording stations in 2017

In August 2017, the U.S. Geological Survey acquired high-resolution P- and S-wave seismic data near six Southern California Seismic Network (SCSN) recording stations in southern California: CI.OLI Olinda; CI.SRN Serrano; CI.MUR Murrieta; CI.LCG La Cienega; CI.RUS Rush; and CI.STC Santa Clara (Figure 1). These strong-motion recording stations are located inside Southern California Edison electrical substations, critical infrastructures that provide essential services to millions of customers. The primary goals of the seismic survey were to understand the potential for amplified ground shaking and to evaluate lateral variability in shear-wave velocity at these sites. We deployed up to 88 geophones at 2-m or 4-m spacing along seven linear profiles surrounding the stations and collocated P- and S-wave sources at ~1-m offset from the geophones. We generated P waves using three types of active sources: a 226-kg vertical accelerated weight-drop (AWD), a 3.5-kg sledgehammer and steel plate combination, and a 2.7-kg hammer and steel plate combination. Active-source S-waves were generated by horizontally striking an aluminum block with a 3.5-kg sledgehammer and by striking a 45 degree-angle aluminum block with a 45 degree-angle AWD. We first deployed vertical-component geophones (40-Hz, SercelTM L40A, sensitivity of 22.34 volts/meter/second) to record P-wave shots, after which the vertical-component geophones were replaced with horizontal-component geophones (4.5-Hz, SercelTM L28-LBH, sensitivity of 31.3 volts/meter/second) to record S-wave shots. All data were recorded using up to two 60-channel Geometrics Stratavisor NX-60TM seismographs with 24-bit analog-to-digital converters. The seismographs were connected to the geophones via refraction cables. Each shot was recorded at a 0.5-ms sampling rate for two seconds, with data recording starting 100 ms before the actual time of the shot. Ambient noise data were recorded with vertical-component geophones at a 2-ms sampling rate for 120 seconds. This report provides the metadata needed to utilize the seismic data. Acknowledgements: We thank Keith Galvin, Koichi Hayashi, Dan Langermann, Tony Martin, Devin McPhillips, Ian Richardson, David Saucedo-Green, Luther Strayer, Nathan Suits, and Alan Yong for assistance in data acquisition. Reference: Subcommittee of the SEG Engineering and Groundwater Geophysics Committee, Pullan, S. E., Chairman, 1990, Recommended standard for seismic (/radar) data files in the personal computer environment: Geophysics, vol. 55, no. 9, p. 1260-1271.