The Strong Motion Earthquake Data Values of Digitized Strong-Motion Accelerograms is a database of over 15,000 digitized and processed accelerograph records from 1933 to 1994. Data were obtained from a variety of structural and geologic environments. Most of the data are available in three levels of processed files. The first type of file contains raw (uncorrected) time, history data points digitized from the analog accelerogram. The second is a filtered, instrument corrected version of the time, history data. This file also contains calculated velocities and displacements obtained by the integration and double integration of the corrected accelerations. The third type of file includes the calculated Fourier and response spectra data. The data are from the United States, Algeria, Argentina, Armenia, Australia, Bulgaria, Canada, Chile, China, El Salvador, Fiji, Germany, Greece, India, Iran, Italy, Japan, Mexico, New Zealand, Nicaragua, Papua New Guinea, Peru, Portugal, Romania, Spain, Taiwan, Turkey, and Uzbekistan. NCEI decommissioned Strong Motion Earthquake Data Values of Digitized Strong-Motion Accelerograms, 1933-1994 in May 2025 with no further updates. Comments and questions may be sent to: ncei.info@noaa.gov.

The Seismicity Catalog Collection is a compilation data on over four million earthquakes dating from 2150 BC to 1996 AD from NOAA's National Geophysical Data Center and U.S. Geological Survey's National Earthquake Information Center. The data include information on epicentral time of origin, location, magnitudes, depth and other earthquake-related parameters. This database is static and is no longer being updated.

The U.S. Geological Survey acquired high-resolution P- and S-wave seismic data across the Frijoles Fault strand of the San Gregorio Fault Zone (SGFZ) at northern Año Nuevo, California in 2012. SGFZ is a right-lateral fault system that is mainly offshore, and prior studies provide highly variable slip estimates, which indicates uncertainty about the seismic hazard it poses. Therefore, the primary goal of the seismic survey was to better understand the structure and geometry of the onshore section of the Frijoles Fault strand of the SGFZ. We deployed 118 geophones (channels) at 5-m spacing along a linear profile centered on the mapped surface trace of the Frijoles Fault and co-located active P- and S-wave sources at ~1-m offset from the geophones. Channel numbers increase from west to east along the profile. We generated P-waves using either a seisgun (www.utep.edu/science/ssf/Manuals/betsy_seisgun.pdf, accessed August 2022) or an accelerated weight-drop and S-waves by horizontally striking an aluminum block on both sides with a sledgehammer. We first deployed vertical-component geophones (40-Hz, SercelTM L40A, sensitivity of 22.34 volts/meter/second) to record P-wave sources, after which we replaced the vertical-component geophones with horizontal-component geophones (4.5-Hz, SercelTM L28-LBH, sensitivity of 31.3 volts/meter/second) to record S-wave sources. Refraction cables connected all geophones to two 60-channel Geometrics Stratavisor NX-60TM seismographs with 24-bit analog-to-digital converters. Each shot was recorded at a 0.5-ms sampling rate for two seconds, with data recording at 100 ms before the actual time of the shot. This data release provides the metadata needed to utilize the seismic data. Data Format and Files We combined each seismic trace for a given shot time into a shot gather, and the traces in each shot gather are ordered by channel numbers (1-118) based on the position of the geophones along the profile. Furthermore, we assigned a unique field number (FFID) to each shot gather, and we combined the shot gathers recorded from both seismographs into two SEG-Y files (Barry et al., 1975), 78023.segy (channels 1 to 60) and marine.segy (channels 61 to 118), which are stored in big-Endian, 4-byte IBM-floating-point format (format code 1). Data samples are in millivolts and can be converted to velocity using the geophone sensitivity values. Metadata for all profiles are contained in two text files and one xml file: PIE12.setup.csv, PIE12.location.csv, and PIE12Metadata.xml. The setup file describes the identification of shots recorded by the two seismographs, channel number, recording stations (geophones), and the source type for both SEG-Y files. The location file describes the channel number, latitude, and longitude of all geophone locations. Reference 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, doi: 10.1190/1.1440530.

This data release includes geodetic time series from high-rate GPS instruments recording 4 earthquakes co-seismically in the near-field – the 2010 Maule, Chile earthquake; the 2012 Nicoya, Costa Rica earthquake; the 2014 Iquique, Chile earthquake; and the 2015 Gorkha, Nepal earthquake. For each earthquake, data (sac files, 1 Hz sampling, ~2-3 minutes around the earthquake origin time) are included in a separate folder. Each sac file provides a time series of ground displacement from the earthquake as recorded at that station. The location of each station is listed in the relevant earthquake file in the “_station_info” folder.

This data release includes geodetic time series from high-rate GPS instruments recording 4 earthquakes co-seismically in the near-field – the 2010 Maule, Chile earthquake; the 2012 Nicoya, Costa Rica earthquake; the 2014 Iquique, Chile earthquake; and the 2015 Gorkha, Nepal earthquake. For each earthquake, data (sac files, 1 Hz sampling, ~2-3 minutes around the earthquake origin time) are included in a separate folder. Each sac file provides a time series of ground displacement from the earthquake as recorded at that station. The location of each station is listed in the relevant earthquake file in the “_station_info” folder.

On August 24, 2021, the U.S. Geological Survey conducted a high-resolution seismic survey between two strong-motion recording stations located at the Veterans Affairs Medical Center (VAMC) in the City of Menlo Park, San Mateo County, California. The stations are National Strong Motion Project Station (NSMP) 1849 in VAMC building 332 and NSMP Station 1870 in VAMC building 334. The primary goals of the seismic survey are to better understand the potential for amplified ground shaking, to evaluate lateral variability in shear-wave velocity, and to calculate time-averaged shear-wave velocity in the upper 30 m of the subsurface (Vs30) at this site using refraction tomography and multichannel analysis of surface waves (MASW) methods.

In May 2015, we acquired high-resolution seismic profiles near six strong motion instruments located in Napa and Solano Counties, California. These strong motion instruments recorded horizontal peak accelerations (PGAs) from 0.329g to 0.611g, which were among the highest recorded in the Napa area during the 24 August 2014 Mw 6.0 South Napa Earthquake. Our goal is to measure the seismic velocities of the underlying geologic material at each strong motion site using P- and S-wave refraction tomography and analysis of surface waves, especially in the upper 30 m of the subsurface.

In May 2015, we acquired high-resolution seismic profiles near six strong motion instruments located in Napa and Solano Counties, California. These strong motion instruments recorded horizontal peak accelerations (PGAs) from 0.329g to 0.611g, which were among the highest recorded in the Napa area during the 24 August 2014 Mw 6.0 South Napa Earthquake. Our goal is to measure the seismic velocities of the underlying geologic material at each strong motion site using P- and S-wave refraction tomography and analysis of surface waves, especially in the upper 30 m of the subsurface.

In November of 2021, the U.S. Geological Survey acquired high-resolution P- and S-wave seismic data at two seismic recording stations in Tulare and Fresno counties, California: Berkeley Digital Seismic Network BK.LIND and BK.KARE. We deployed 60 DTCC SmartSolo 3-component nodal seismometers (“nodes”) at 2-m intervals along a linear array at each seismic recording station. The nodes recorded seismic data continuously at a 0.5-ms sampling interval, and shot timing was recorded by GPS event capture hardware to precisely determine the shot times. We generated active-source P-waves by vertically striking a steel plate with a 3.5-kg sledgehammer, and active-source S-waves by horizontally striking an aluminum block with a 3.5-kg sledgehammer. The active-sources were generated at about 1-m offset from the nodes along the arrays.