Homeland Infrastructure Foundation-Level Data (HIFLD) geospatial data sets containing information on Historical Significant Earthquake Locations.

Epicenters of known M≥5 earthquakes from 1769 to 2016 are shown for California and a 100 km area bordering the state. Earthquakes are grouped by: M = 5-6; M = 6-7; M = 7+.

Epicenters of known M≥5 earthquakes from 1769 to 2016 are shown for California and a 100 km area bordering the state. Earthquakes are grouped by: M = 5-6; M = 6-7; M = 7+.

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 This database is static and is no longer being updated.

This Data Release contains an updated version of the San Andreas catalog of low-frequency earthquakes (LFEs): Shelly, D. R. (2017), A 15 year catalog of more than 1 million low-frequency earthquakes: Tracking tremor and slip along the deep San Andreas Fault, J. Geophys. Res. Solid Earth, 122, 3739–3753, doi:10.1002/2017JB014047. This catalog contains 88 LFE families, with each family consisting of events detected by cross-correlation with the associated waveform template. These templates were identified and located by Shelly and Hardebeck (2010): Shelly, D. R., and J. L. Hardebeck (2010), Precise tremor source locations and amplitude variations along the lower-crustal central San Andreas Fault, Geophys. Res. Lett., 37, L14301, doi:10.1029/2010GL043672. For completeness, we repeat the original catalog information provided in the supplement of Shelly (2017) below, with minor modifications: Catalog Time-Period and Format: The low-frequency earthquake catalog spans from April 2001 to 30 April 2024 and contains 1,528,117 events. Format: YYYY MM DD s_of_day HH mm ss.ss ccsum meancc med_cc seqday ID latitude longitude depth n_chan Explantions: YYYY MM DD (year month day) - Event time (template start time in UTC - ~1s prior to first S-wave arrival time at an HRSN station) s_of_day - Event time (template start time in UTC - ~1s prior to first S-wave arrival time at an HRSN station), second of the day (i.e. 0-86400), HH mm ss.ss (hour, minute, second) - Event time (template start time in UTC- ~1s prior to S-wave arrival time at first HRSN station) ccsum - correlation sum across all stations (must exceed 4.0) meancc - mean correlation among stations with data med_cc - median correlation seqday - sequential day since March 1, 2001 ID - reference ID of family latitude longitude depth - estimated location for that family (Shelly and Hardebeck, 2010) n_chan - number of data channels existing for event (some channels may exist, but not have good data) Family IDs: Each family has an associated identification code, which is a number followed by 1-4 ‘s’. The family IDs are almost meaningless and are simply used as unique identifiers. Originally the numeric code was taken from the second of the day at which the initial template for this family occurred. The number of ‘s’ indicates the number of iterations of stacking and cross-correlation that were applied to derive the template waveforms (see Methods). The lower amplitude and more distant sources typically benefitted from multiple iterations of stacking and cross correlation, before the final template stabilized in its detection set. Data channels Used (station.channels): GHIB.13, EADB.123, JCSB.1, FROB.123, JCNB.123, VCAB.123, MMNB.123, CCRB.123, LCCB.123, SMNB.123, RMNB.123, SCYB.123 JCNB failed in 2008 and was replaced by a shallow sensor. New sensor not used. RMNB failed in 2011 and was not replaced. GHIB.2 was never operational JCSB.23 have poor signal to noise and are not used. VARB was replaced with a new sensor at a new depth in 2003, and this station was not used in original template formation. As of 2024, detection capabilities were substantially degraded with a maximum of 16 channels of data available for detection. This is due to outages in GHIB (since 2020), FROB (since 2023), VCAB (since 2023), and CCRB (since 2022), in addition to the outages described above. It is unclear when/if these stations might be repaired in the future. Channel swap on FROB, VCAB (after BP->SP channel swap, before 2011-7-14): 2011/4/21-2011/7/14: Swap VCAB.2 and VCAB.3 2010/11/10-2011/7/14: Swap FROB.2 and FROB.3 Disregard mean correlation, enforce network correlation sum only (because of poor but present data): 2012/2/13-2014/4/23 Polarity corrections during initial processing: CCRB.123, correct for reversed polarity from 2001-6-1 to 2001-12-13. FROB.123, correct for reverse polarity from 2010/12/10-2011/4/7 MMNB.123, correct for reverse polarity from 2010/12/10-2011/4/7 FROB.23, correct for reverse

Earthquake-triggered ground-failure, such as landsliding and liquefaction, can contribute significantly to losses, but our current ability to accurately include them in earthquake hazard analyses is limited. The development of robust and transportable models requires access to numerous inventories of ground failure triggered by earthquakes that span a broad range of terrains, shaking characteristics, and climates. We present an openly accessible, centralized earthquake-triggered ground-failure inventory repository in the form of a ScienceBase Community to provide open access to these data, and help accelerate progress. The Community hosts digital inventories created by both USGS and non-USGS authors. We present the original digital inventory files (when available) as well as an integrated database with uniform attributes. We also summarize the mapping methodology and level of completeness as reported by the original authors for each inventory. This document describes the steps taken to collect, process, and compile the inventories and the process for adding additional ground-failure inventories to the ScienceBase Community in the future.

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.

The Significant Earthquake Database is a global listing of over 5,700 earthquakes from 2150 BC to the present. A significant earthquake is classified as one that meets at least one of the following criteria: caused deaths, caused moderate damage (approximately $1 million or more), magnitude 7.5 or greater, Modified Mercalli Intensity (MMI) X or greater, or the earthquake generated a tsunami. The database provides information on the date and time of occurrence, latitude and longitude, focal depth, magnitude, maximum MMI intensity, and socio-economic data such as the total number of casualties, injuries, houses destroyed, and houses damaged, and $ dollage damage estimates. References, political geography, and additional comments are also provided for each earthquake. If the earthquake was associated with a tsunami or volcanic eruption, it is flagged and linked to the related tsunami event or significant volcanic eruption.

The earthquake catalog was generated in August 2018 using the standard National Seismic Hazard Model methodology (Mueller, 2019) for the central and eastern United States. Pre-existing catalogs were merged, duplicate records were removed, the catalog was declustered, and induced earthquakes were removed. The final catalog contains 6802 records, M2.5–7.8, and extends from 1568 through July 2018.