About the Real-time Earthquake Maps

General Information

Why is the earthquake that was reported/recorded by network X, or that I felt, not on the map/list? and other Frequently Asked Questions (FAQ) about the Latest Earthquakes information.

USGS Earthquake Magnitude Policy

The earthquake map projection is Web Mercator, and the reference model is WGS-84.

Realtime Earthquakes Data Sources & Contributing Networks

US, International, and Offshore Regions

Alaska

Central and Southeastern US

Hawaii

Nevada

Northeast

Northern California

Pacific Northwest

Puerto Rico

Southern California

Utah and Yellowstone

All members of the ...

Map Information and Data Sources

Map Software

Topographic Data

This data was acquired from the General Bathymetric Chart of the Oceans (GEBCO) project at: http://www.gebco.net/data_and_products/gridded_bathymetry_data/. The data in its original form is 30 arc-second bathymetry data for the entire globe. Land data is supplemented in most cases by Shuttle Radar Topography Mission (SRTM30) digital elevation model. For detailed cache levels, this data was resampled dynamically by ArcGIS Desktop software to give users more elevation detail.

Street/Aerial Data

Street and Aerial data, imagery and map information provided by MapQuest, OpenStreetMap and contributors, CC-BY-SA. Green boundaries usually just offshore are "administrative boundaries". Please see the OpenStreetMap website for more information on the basemaps they provide.

Plate Boundary Data

This data was acquired from the Peter Bird Plate Boundary Dataset. Information about this data can be found at: http://peterbird.name/publications/2003_PB2002/2003_PB2002.htm.
NOTE: Included plate boundaries were chosen appropriately based on scale.

Water Data

State and International Boundaries

Placename Data:

  • The placenames were derived from US Census data, such as from http://www.census.gov/geo/www/gazetteer/places2k.html. International places were gathered from a specially created USGS catalog. Selected places were based on minimum population values that were specified for each particular region. If there are too many places on any map, a separation distance algorithm was used to limit the number of places that appear on the map. If no places appeared on the map, a lower population threshold was used to plot smaller places.

Faults

  • The data used for these features was acquired from the Hazard Faults Database for the United States.
  • Known hazardous faults and fault zones in California and Nevada

    The known active fault segments in California and Nevada can be seen in Figure 25 of USGS Open-File Report 96-532: National Seismic Hazard Maps, June 1996: Documentation" by Arthur Frankel, Charles Mueller, Theodore Barnhard, David Perkins, E.V. Leyendecker, Nancy Dickman, Stanley Hanson, and Margaret Hopper.

    For northern California, the potential sources of earthquakes larger than magnitude 6 are documented in Open-File Report 96-705 by the Working Group on Northern California Earthquake Potential (chaired by Jim Lienkaemper).

    For the state as a whole, see "Probabilistic seismic hazard assessment for the State of California" by Petersen, M. D., Bryant, W.A., Cramer, C.H., Cao, T., Reichle, M.S., Frankel, A.D., Lienkaemper, J.J., McCrory, P.A., and Schwartz, D.P, 1996 (California Division of Mines and Geology Open-File Report 96-08; [published jointly as] U.S. Geological Survey Open-File Report 96-706).

    The faults and fault zones described in these reports are known to have been active in the last 2 million years and are thought to pose a measurable hazard.

    For California the faults on the individual zoomed-in and special maps come from the three categories of faults believed to have been active in the last 700,000 years shown on the "Preliminary Fault Activity Map of California" by C.W. Jennings (1992, California Division of Mines and Geology Open-File Report 92-03). This map has been superseded by Jennings, C.W., 1994, Fault activity map of California and adjacent areas, with locations and ages of recent volcanic eruptions: California Division of Mines and Geology, Geologic Data Map No. 6, map scale 1:750,000.

    For Nevada the faults on the individual zoomed-in and special maps come from USGS Open-File Report 96-532 mentioned above.

    For more information on files and images discussed above visit the1996 Documentation Page

    Highways and Roads

    Global and US Hazard

    Network Contacts

    National Earthquake Information Center (NEIC)

    U.S. Geological Survey
    National Earthquake Information Center
    Box 25046, DFC, MS 967
    Denver, Colorado 80225

    Earthquake Information Line: 303-273-8500 (24x7 Opertions)
    Fax: 303-273-8450
    Web Page: http://earthquake.usgs.gov/regional/neic/
    E-mail: sedas@neis.cr.usgs.gov

    Alaska Earthquake Information Center (AEIC)

    Alaska Earthquake Information Center (AEIC)
    Geophysical Institute
    University of Alaska Fairbanks
    903 Koyukuk Drive
    Fairbanks, AK 99775-7320

    Voice: 907-474-7320
    Fax: 907-474-7125
    Web Page: http://www.aeic.alaska.edu/
    E-mail: webmaster@giseis.akaska.edu

    West Coast and Alaska Tsunami Warning Center/NOAA/NWS

    West Coast and Alaska Tsunami Warning Center/NOAA/NWS
    910 S. Felton St.
    Palmer, AK 99645

    Web Page: http://wcatwc.arh.noaa.gov/
    E-mail: wcatwc@wcatwc.gov

    Cooperative New Madrid Seismic Network

    Center for Earthquake Research and Information
    Campus Box 526590
    The University of Memphis
    Memphis, TN 38152

    Voice: 901-678-2007
    Fax: 901-678-4734
    Web Page: http://www.ceri.memphis.edu/
    E-mail: withers@ceri.memphis.edu

    Inter-Mountain West Seismic Networks

    Earthquake Studies Office
    Montana Bureau of Mines and Geology
    1300 West Park Street
    Butte, MT 59701-8997

    Voice: 406-496-4332
    Fax: 406-496-4451
    Web Page: http://mbmgquake.mtech.edu/
    E-mail: mstickney@mtech.edu

    Nevada Seismological Laboratory
    University of Nevada, Reno
    Reno, Nevada

    Voice: 775-784-4975
    Fax: 775-784-4165
    Web Page: http://www.seismo.unr.edu/

    University of Utah Seismograph Stations
    135 South 1460 East
    Salt Lake City, Utah 84112-0111

    Voice: 801-581-6274
    Fax: 801-585-5585
    Web Page: http://www.seis.utah.edu/
    E-mail: webmaster@seis.utah.edu

    Hawaiian Volcano Observatory Network

    U.S. Geological Survey
    Hawaiian Volcano Observatory
    P O Box 51
    Hawaii National Park, Hawaii 96718

    Voice: 808-967-7328
    Fax: 808-967-8890
    Web Page: http://hvo.wr.usgs.gov/
    Web Page: http://elsei.wr.usgs.gov/results/seismic/recenteqs/
    E-mail: hvowebmaster@hvo.wr.usgs.gov

    Pacific Tsunami Warning Center

    US Dept of Commerce
    91-270 Fort Weaver Road
    EWA Beach, HI 96706-2928

    Voice: 808-689-8207
    Web Page: http://ptwc.weather.gov
    E-mail: webmaster@ptwc.noaa.gov

    Northeast

    Lamont-Doherty Cooperative Seismographic Network (LCSN)
    Lamont-Doherty Earth Observatory of Columbia University
    Palisades, NY 10964

    Voice: 845-365-8365
    Fax: 845-365-8150
    Web Page: http://www.ldeo.columbia.edu/LCSN/
    E-mail: jha@ldeo.columbia.edu

    Weston Observatory
    Department of Geology and Geophysics, Boston College
    381 Concord Road Weston, MA 02493-1340

    Voice: 617-552-8300
    Fax: 617-552-8388
    Web Page: http://www.bc.edu/bc_org/avp/cas/wesobs/
    E-mail: weston.observatory@bc.edu

    Northern California Seismic Network

    U.S. Geological Survey
    Seismology Section
    345 Middlefield Road - MS 977
    Menlo Park, CA 94025

    Earthquake Info: 650-329-4025
    Voice: 650-329-4085
    Fax: 650-329-5163
    Web Page: http://quake.wr.usgs.gov/
    E-mail: ncsn@andreas.wr.usgs.gov

    U.C. Berkeley Seismological Laboratory
    207 McCone Hall
    U.C. Berkeley
    Berkeley, CA 94720-4760

    Earthquake Info: 510-642-2160
    Voice: 510-642-3977
    Fax: 510-643-5811
    Web Page: http://www.seismo.berkeley.edu/
    E-mail: www@seismo.berkeley.edu

    Pacific Northwest Seismic Network

    Univ. of Washington, Dept. of Earth and Space Sciences
    Box 351310
    Seattle, WA 98195-1310

    Earthquake Info: 206-543-7010
    Voice: 206-685-8180 (lab) or 206-543-1190 (department)
    Fax: 206-543-0489
    Web Page: http://www.ess.washington.edu/SEIS/PNSN/welcome.html
    E-mail: seis_info@ess.washington.edu

    Puerto Rico Seismic Network

    Puerto Rico Seismic Network
    Department of Geology
    University of Puerto Rico at Mayagüez
    PO Box 9017
    Mayagüez, PR 00681-9017

    Voice: 787-833-8433
    Fax: 787-265-1684
    Web Page: http://redsismica.uprm.edu/english/
    E-mail: staff@redsismica.uprm.edu

    Southern California Seismic Network

    Southern California Seismic Network
    U.S. Geological Survey - Caltech Seismological Laboratory
    Pasadena, California

    EQ Info: 626/395-6977
    Voice: 626/583-7823 or 626/395-6919
    Fax: 626/583-7827
    Web Page: http://earthquake.usgs.gov/regional/sca/
    Web Page: http://www.seismolab.caltech.edu/

    Disclaimers

    Earthquakes Included and Not Included on Maps and Lists

    The maps and lists show events which have been located by the USGS and contributing agencies within the last 30 days. They should not be considered to be complete lists of all events in the US and adjacent areas and especially should not be considered to be complete lists of all events M4.5+ in the world.

    In most cases, we locate and report on earthquakes worldwide of magnitude 5.0 and larger in 30 minutes or less. Additionally, we locate and report on earthquakes magnitude 4.0 and larger within the contiguous US and populated regions of Alaska within 30 minutes. Earthquakes of magnitude 2.0 or greater within the US and populated regions of Alaska are often rapidly reported if they occur within the region of a contributing local seismic network.

    We may not rapidly locate earthquakes smaller than 5.0 outside the US unless they have caused significant damage or are widely felt. Earthquakes this small rarely cause significant damage. At times, some other agency may report an earthquake with a larger magnitude than what we compute from our data, especially for non-US events near magnitude 5.0. If our magnitude for the event is less than magnitude 5.0, we may not issue a rapid report for it.

    Earthquakes occurring outside the US and smaller than about magnitude 4.5 can be difficult for the USGS to locate if there are not enough data. The USGS continues to receive data from observatories throughout the world for several months after the events occur. Using those data, we add new events and revise existing events in later publications. For a description of these later publications and the data available, see Scientific Data.

    If you think there is a missing earthquake on our maps and lists, there possibly is. Please see the national and regional links for the area of interest on these webpages:

    Magnitudes

    The magnitude which the USGS considers official for this earthquake is indicated at the top of this page. This was the best available estimate of the earthquake’s size, at the time that this page was created. Other magnitudes associated with web pages linked from here are those determined at various times following the earthquake with different types of seismic data. Although they are legitimate estimates of magnitude, the USGS does not consider them to be the preferred (“official” magnitude for the event.

    Regional Names and References to Places

    The list of reference places from the earthquake epicenter is automatically created using a database of placenames and an algorithm that chooses several locations as references. The number of placenames depends on the location of the earthquake. We use the GeoRef database and supplement it with additional placenames for locations distant from any cities (such as ocean ridges).

    As an agency of the U.S. Government, we are expected to use the names and spellings approved by the U.S. Board on Geographic Names. Any requests to approve additional names should be made to the U.S. Board on Geographic Names. For more information, see their website at http://earth-info.nga.mil/gns/html/.

    The region name is an automatically generated name based on the Flinn-Engdahl (F-E) seismic and geographical regionalization scheme. The boundaries of these regions are defined at one-degree intervals and therefore differ from irregular political boundaries. For example, F-E region 545 (Northern Italy) also includes small parts of France, Switzerland, Austria and Slovenia and F-E region 493 (Chesapeake Bay Region) includes all of the State of Delaware, plus parts of the District of Columbia, Maryland, New Jersey, Pennsylvania and Virginia. Beginning with January 2000, the 1995 revision to the F-E code has been used in the QED and PDE listings. This revision includes 28 additional regions, which were defined by subdividing larger regions to provide better coverage for Northwest Africa, Southeast Asia and seismic zones along oceanic ridges. In recent years, additional polygons have been defined in some areas to agree better with irregular political boundaries and to provide some additional detail.

    See http://earthquake.usgs.gov/learn/topics/flinn_engdahl.php

    References

    • Young, J.B., Presgrave, B.W., Aichele, H., Wiens, D.A. and Flinn, E.A., 1996, The Flinn-Engdahl Regionalisation Scheme: the 1995 revision, Physics of the Earth and Planetary Interiors, v. 96, p. 223-297.
    • Flinn, E.A., Engdahl, E.R. and Hill, A.R., 1974, Seismic and geographical regionalization, Bulletin of the Seismological Society of America, vol. 64, p. 771-993.
    • Flinn, E.A., and Engdahl, E.R., 1965, A proposed basis for geographical and seismic regionalization, Reviews of Geophysics, vol. 3, p. 123-149.