Earthquake data from the

U.S. National Seismograph

Network and other stations

feed into USGS computers, located in Golden, Colo., via

satellite transmissions and through the Internet.

information. The United States National

Seismograph Network (USNSN), operated by

the USGS, provides uniform coverage of the

whole Nation and integrates data from the

regional networks. The NEIC rapidly reports

earthquakes to Federal, State, and local emergency managers, public utilities, the media,

and the public. The RSN’s fulfill a similar role

within their regions. The cooperation and

coordination of the RSN’s and the USNSN is

organized through the Council of the National

Seismic System (CNSS), of which the USGS

is the steward. 

Understanding Earthquake Hazards Across the United States

More than 2,500 seismograph stations

monitor earthquakes throughout the

conterminous United States, Alaska, and

Hawaii. The stations are grouped into regional

networks operated by local institutions. The

U.S. Geological Survey (USGS) supports

many of these regional networks and operates

its own nationwide network. The regional

seismograph networks (RSN’s) provide information about earthquakes to the USGS

National Earthquake Information Center

(NEIC) in Colorado, which serves as a national point of contact for distributing earthquake

Monitoring Monitoring Earthquakes Earthquakes

Across the United States Across the United States

T hose who plan for and respond to earthquake disasters, and those who study

earthquakes, require timely notification of earthquake occurrences and information to mitigate losses. Earthquake events throughout the United States are currently monitored by sophisticated systems that provide the notification and information

needed by decision makers before and during times of crisis. The national and regional

earthquake monitoring systems for the United States have evolved into one of the

world’s finest emergency-management and research tools.

USGS Fact Sheet 146-97 USGS Fact Sheet 146-97

1997

U.S. Department of the Interior

U.S. Geological Survey
The USNSN determines the location and

magnitude of significant earthquakes anywhere in the United States within minutes,

while the RSN’s provide this information for

earthquakes in their regions within seconds.

Together, the RSN’s and the USNSN provide

(1) comprehensive, reliable, and cost-effective

earthquake monitoring of the Nation, (2)

highly accurate recordings of even the largest

earthquakes, and (3) high-resolution mapping

of faults in seismically active areas. In the

aftermath of a major earthquake, the

USGS/NEIC and the RSN’s rapidly provide

earthquake information, including detailed

interpretations to assist disaster-response

activities. The USGS/NEIC uses the USNSN

to assist other Federal agencies in tsunami

warnings, overseeing nuclear powerplant

safety during earthquakes, and discriminating

nuclear blasts from earthquakes under

nuclear- test-ban agreements.

SEISMIC MONITORING

• Real-time hazards information for emergency management and the general public

• General information for public officials,

utilities, the engineering community, and

the media

• Earthquake catalog for earthquake hazards

assessments

• Seismic waveform archive for applied and

basic research

National Component (USNSN)

• National real-time advisories within 

minutes

• Uniform earthquake monitoring of the

Nation

• Precise recordings of medium to large

earthquakes

Regional Component (RSN’s)

• Regional real-time advisories within 

seconds

• Detailed monitoring of earthquake-prone

areas

• Precision mapping of faults

• Local expertise on earthquake hazards to

increase public awareness and safety 

Each USNSN station

consists of a system

of sophisticated

seismometers, dataacquisition system,

and satellite

telecommunications

equipment. USNSN

stations provide

high-quality, realtime information on

earthquake occurrences directly to

the USGS National

Earthquake

Information Center

(NEIC) in Colorado

and to cooperators

throughout the 

network.

For the Nation,

seismic monitoring offers a

wide variety of

benefits

focused on

minimizing

loss of life and

property that

result from

earthquakes,

and understanding earthquake phenomena for

earthquakehazards

planning.

USNSN Stations

USNSN Stations (Planned)

Cooperating Stations

Cooperating Stations (Planned)

USNSN Stations
This seismogram of a magnitude 5.0 aftershock of the 1994

Northridge, California, earthquake was recorded at a

USNSN station in Tonopah, Nevada. The P-wave (traveling

rapidly through the Earth) was recorded first; the S-wave

(traveling more slowly through the Earth) was recorded

about 40 seconds later and produced significantly stronger

ground vibrations. Seismograms from many stations that

record the same event allow scientists to determine such

factors as the time, location, type of faulting, and energy

release of an earthquake.

Advanced seismic sensors (inset) are

installed at USNSN sites to measure Earth

movements. 

Distributing Uniform Earthquake

Information Nationwide

The USGS and the RSN’s are currently developing agreements on common methods, format, and procedures for reporting earthquake

information. This ongoing program effectively integrates the USNSN and the RSN’s into a

single National Seismic System. Part of this

effort includes acquiring and developing new

software to connect all seismograph networks

across the Nation. Earthquake data from any

network then will be immediately available to

all networks nationwide. For example, a

requester in New York will be able to obtain

immediate information on an earthquake in

Oregon from a local RSN in New York, rather

than trying to communicate with a more distant RSN.

Activities of the seismograph networks

nationwide are coordinated by the Council of

the National Seismic System (CNSS), which

fosters development and cooperation for

improved regional and national earthquake

reporting. Details about the CNSS and its

member seismograph networks may be

viewed on the World Wide Web (WWW) at

the following Uniform Resource Locator

(URL):

http://www.cnss.org/

Current earthquake activity is posted directly

to the WWW as earthquakes occur. Locations

of important earthquakes nationwide are

reviewed by analysts and listed on the WWW

within about an hour. In other areas, notably

central California, earthquake locations automatically appear on the WWW in about a

minute. Examples, which include a variety of

earthquake parameters, and maps of epicenters, can be viewed on the WWW at the following URL’s:

http://quake.wr.usgs.gov/recenteqs

http://wwwneic.cr.usgs.gov/

P-wave

S-wave

0 50 seconds
For more information contact:

U.S. Geological Survey

National Earthquake Information Center

(303) 273-8500

Mailing address:

Federal Center, Box 25046, MS 967

Denver, CO 80225-0046 USA

http://wwwneic.cr.usgs.gov/

University of Utah Seismograph Stations,

Salt Lake City

University of Washington, Seattle

U.S. Advanced Research Projects Agency

U.S. National Park Service, Yellowstone

National Park

U.S. Nuclear Regulatory Commission

U.S. Air Force Technical Applications Center,

Patrick Air Force Base, Florida

U.S. Bureau of Reclamation

U.S. Department of Energy, Sandia National

Laboratories

Virginia Polytechnic Institute and State

University Seismological Observatory,

Blacksburg

West Coast/Alaska Tsunami Warning Center,

Palmer, Alaska

Wyoming Geological Survey, Laramie

Boston College, Weston, Mass.

California Institute of Technology, Pasadena

Delaware Geological Survey

Incorporated Research Institutions for

Seismology

Lamont-Doherty Earth Observatory of

Columbia University

Lawrence Livermore National Laboratory

Pacific Tsunami Warning Center, Ewa Beach,

Hawaii

Saint Louis University, Saint Louis, Mo.

University of Alaska, Fairbanks

University of California, San Diego

University of California, Berkeley

University of Memphis

University of Nevada, Reno

University of North Carolina at Chapel Hill

University of South Carolina

The USGS supports the regional seismograph networks (RSN’s) that monitor the areas of the United States outlined in red. Other RSN’s are self-supporting. The Council of the National Seismic System (CNSS) coordinates

activities of the RSN’s and the United States National Seismiograph Network (USNSN). White circles indicate magnitude 2.0 and greater earthquakes recorded between July 1995 and August 1996.

Regional Seismograph Networks

The USGS and its

cooperators have

been steadily

developing this

vast, interconnected monitoring and communications system

for many years.

Continually using

technological

advances to

improve the system and interpret

the information it

produces, USGS

earth scientists

are serving primary needs for

the Nation’s

approach and

response to

earthquake

hazards.

By

Raymond P. Buland, Harley M. Benz, and

William M. Brown III

Graphic design by

Eleanor M. Omdahl and Margo L. Johnson

Cooperating Organizations