Publications, earthquake maps, real-time products, and derived datasets.
USGS provides several ways to obtain real-time earthquake lists, in addition to web-based maps and event pages. Earthquakes are broadcast (i.e., through email, CSV, ATOM, CAP alerts, etc.) within a few minutes for California events, and within 30-minutes for worldwide events.
This site provides a single source for all USGS supported products associated with a particular earthquake. Specifically, the catalog includes the date/time of the earthquake along with the following products (if available): location, magnitude(s), depth, moment tensor, focal mechanism, DYFI, ShakeMap, PAGER, event posters, tectonic summaries, Finite Fault, Exposure, lists of significant events, phase data, residuals. Customized searching is available along with output download capabilities.
- ANSS Comprehensive Earthquake Catalog (ComCat) - Parametric Data
- Preliminary Determination of Epicenters (PDE)
- Regional Seismic Networks (regional catalogs will be loaded into ComCat)
Specialized Earthquake Catalogs
- Double Difference Relocation Catalogs:
- Centennial Earthquake Catalog - global catalog of locations and magnitudes of instrumentally recorded earthquakes from 1900 to 2008, relocated with same method.
- NEIC Mining Seismicity Catalog
- Seismicity of Russia and the Former Soviet Union
- International Seismological Summary (ISS) Earthquake Catalog (1918-1963)
- Earthquake Catalog for Stable Continental Regions - Intraplate Earthquakes (495-2002)
USGS collects seismic data from a variety of stations operated regionally, nationally, and globally. Data are divided into three primary categories: broadband stations are designed to record weaker motions from either small or distant earthquakes, strong motion stations are designed to record on-scale waveforms from larger earthquakes or earthquakes closer to the station. Portable instruments (of either type) are also deployed to collect data for special studies including aftershock studies of noteworthy earthquakes. These waveform data are available at the following sites:
- Broadband Data - Incorporated Research Institutions for Seismology (IRIS)
- Strong Motion Data:
- Weak Motion data from regional networks:
- Aftershock Deployments
- General Earthquake Observation System (GEOS)
Fault slip during earthquakes produces surface displacements that complement waveforms from seismometers. Since about 1970, USGS scientists have used a variety of geodetic techniques to infer which faults are active and to estimate seismic hazard. USGS also provides funding support to other institutions making geodetic observations. Currently to make geodetic observations the USGS uses the Global Positioning System (GPS) and also other techniques (creepmeters, tiltmeters, strainmeters, magnetometers, pore pressure monitors).
USGS processes its own GPS data, plus data from its cooperators and other network operators; these results are available as time series of daily GPS positions. USGS also processes GPS data in real time from instruments in USGS-operated and other networks in the Bay Area and Southern California. The processed position streams are available in real time online.
- Crustal Deformation Data (creepmeters, tiltmeters, strainmeters, magnetometers, pore pressure monitors)
- Crustal Deformation Data Plots - recent measurements update hourly
- Unprocessed USGS Campaign GPS data and Bay Area Continuous GPS data (raw and RINEX) at NCEDC
- Unprocessed USGS Southern California Continuous GPS data (raw and RINEX) at SOPAC
- USGS GPS Time Series and Station Velocities (daily processed results, campaign and continuous)
- Real-time GPS Positions:
- USGS once used Electronic Distance Measurement (EDM) with two different instruments:
Earth Structure and Site Response
USGS conducts seismic reflection and refraction profiling to assess Earth structure and 3-D velocities. We also use earthquakes and other seismic data to model Earth structure, including the geometry of subduction zones. Most data obtained from active source studies are archived at IRIS and/or at the National Geophysical Data Center. USGS also provides access to certain data sets through its web site. Links to data are as follows:
- Global Crustal Database
- USGS Global Vs30 Server
- USGS Vibroseis Seismic Reflection Data
- USGS Marine Seismic Reflection Data
- Maps of Quaternary Deposits:
- San Francisco Bay Region Geology and Fault Maps
Ground Motion and Site Conditions
Intense ground shaking during large earthquakes can damage or even cause failure of engineered structures such as buildings, bridges, highways, and dams. Sustained strong shaking can also trigger ground failures, such as rock falls, landslides, earth flows and liquefaction. Strong motion seismology uses special sensors, called accelerometers, to record these large-amplitude ground motions and the response of engineered structures to these motions. Recordings of large-amplitude seismic waves near the earthquake source can be used to investigate the fault motions that produced the earthquake.
Site response and ground motion studies use standard seismometers and oil-industry standard geophones to measure the local shaking from natural and man-made sources. These measurements help predict differential, site-dependent ground motion resulting from earthquakes. This information is used to upgrade building codes, to design earthquake-resistant structures, and to predict the patterns of strong shaking from future large earthquakes. Rapid reporting of shaking levels also helps to focus emergency response efforts in areas where damage is likely to be the greatest.
- Cone Penetration Testing
- Photographs Showing Ground Failure and Earthquake Damage
- Landslide hazard maps:
- GEOS earthquake and aftershock data
- Ground Motion Field Investigations & Seismic Arrays
Hazard Assessment Data and Models
USGS conducts seismic hazard assessments for the Nation, and on a case by case basis, for other parts of the world. The maps utilize a number of different primary data sources, including seismicity catalogs, fault databases, and in some cases, geodetic deformation models. These input data sets, along with the resulting hazard models, are available in the Hazards section of the website.
- Soil Type and Shaking Hazard in the San Francisco Bay Area
- Shaking Hazard in Alameda County, CA
- Liquefaction Hazard in San Francisco Bay Area, NW Alameda County, N Santa Clara Valley, CA
Faults and Folds
- Northern California LiDAR Hillshades (KMZ)
- LiDAR databases:
- San Francisco Bay Region Geology and Geological Hazards (maps)
- Quaternary Fault Maps (publications):
- National Quaternary Fault & Fold Database and Maps
Geologic and Seismic Models
Other Data Sources
- San Francisco Bay Area Data & Maps
- Parkfield Geophysical Data
- 1868 Hayward Fault Data & Products
- 1906 San Francisco Earthquake Data & Products
- 1989 Loma Prieta, CA Earthquake Data & Products
- SAFOD Data
- Flinn-Engdahl Regionalization Files
- Rupture Directions for Selected Northern California Earthquakes
Information and Data Outside of USGS
Non-USGS sites that host various geophysical, geodetic, and geologic data pertinent to earthquake studies: