This map shows seven earthquake-generated tsunami events in the United States from the 

years 900 to 1964. The earthquakes that caused these tsunamis are: Prince William Sound, 

Alaska, 1964, magnitude 9.2; Chile, 1960, magnitude 9.5; Alaska, 1946, magnitude 7.3; Puerto 

Rico/Mona Rift, 1918, magnitude 7.3 to 7.5; Virgin Islands, 1867, magnitude undetermined; 

Cascadia, 1700, magnitude 9; and Puget Sound, 900, magnitude 7.5. Map not to scale. 

Sources: National Geophysical Data Center, NOAA, USGS

Crescent City, Calif., is heavily damaged 

following a tsunami generated in Alaska on 

March 28, 1964. (University of CaliforniaEERC photo)

 Tsunami Impacts USGS Science Priorities

• The 2004 Indian Ocean tsunami reached 

 heights of 65 to 100 feet in Sumatra, 

 caused more than 200,000 deaths from 

 Indonesia to East Africa, and registered 

 on tide gauges throughout the world.

• The 1964 Alaska tsunami led to 110 

 deaths, some as far away as Crescent 

 City, Calif.

• In 1918, an earthquake and tsunami

 killed 118 people in Puerto Rico. Sev

 eral such events have struck this region

 in historic times

• A tsunami that originated along the 

 Washington, Oregon, and California 

 coasts in 1700 overran Native American 

 fishing camps and caused damage 

 in Japan.

• Identify and quantify tsunami sources, 

 such as earthquake faults, volcanoes, 

 and landslides

• Assess tsunami sources and hazards 

 and model tsunami generation

• Improve understanding of how tsuna-

 mis are generated and incorporate this 

 information into probabilities of tsu-

 nami hazards in different areas

• Assess tsunami inundation hazards by 

 interpreting tsunamis

USGS Science Helps Build Safer Communities

Tsunami Hazards—A National Threat

U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2006–3023

February 2006 Printed on recycled paper

 Tsunami events in the United States and Puerto Rico A Real Risk for the United States

In December 2004, when a tsunami 

killed more than 200,000 people in 11 

countries around the Indian Ocean, the 

United States was reminded of its own 

tsunami risks.

In fact, devastating tsunamis have 

struck North America before and are sure 

to strike again. 

Especially vulnerable are the five 

Pacific States—Hawaii, Alaska, Washington, Oregon, and California—and the 

U.S. Caribbean islands. 

In the wake of the Indian Ocean 

disaster, the United States is redoubling 

its efforts to assess the Nation’s tsunami 

hazards, provide tsunami education, and 

improve its system for tsunami warning. 

The U.S. Geological Survey (USGS) 

is helping to meet these needs, in partnership with the National Oceanic and 

Atmospheric Administration (NOAA) 

and with coastal States and counties.

**1964 Prince William Sound

 1960 Chile

 1946 Alaska

 1918 Puerto Rico / Mona Rift

 1867 Virgin Islands

 1700 Cascadia

 900 Puget Sound

*
 Tsunami Facts

• Tsunamis are triggered by earthquakes, volcanic eruptions, submarine land-

 slides, and by onshore landslides in which large volumes of debris fall into the 

 water. All of these triggers can occur in the United States.

• If a tsunami-causing disturbance occurs close to the coastline, a resulting tsunami 

 can reach coastal communities within minutes.

• Although many people think of a tsunami as a single, breaking wave, it typically 

 consists of multiple waves that rush ashore like a fast-rising tide with power-

 ful currents. Tsunamis can travel much farther inland than normal waves. 

 For More Information

http://walrus.wr.usgs.gov/tsunami/—

USGS tsunami research

http://woodshole.er.usgs.gov/projectpages/caribbean/—USGS research 

into tsunami hazards in the Caribbean

http://www.usgs.gov/

An automobile, carried by surging water 

during the December 26, 2005, Indian 

Ocean tsunami, lies crumpled in a building 

in Banda Aceh, Indonesia. (USGS photo/Guy 

Gelfenbaum)

Following the December 26, 2005, Indian 

Ocean tsunami, debris and standing water 

are the only things left in parts of Banda 

Aceh, Indonesia. (USGS photo/Guy Gelfenbaum)

Tsunami Warnings

In 2005, the President’s tsunami-warning initiative directed $37.5 million to 

the USGS and NOAA to improve the 

Nation’s domestic tsunami detection and 

warning system. 

As part of that commitment, the USGS 

has received $13.5 million to strengthen 

its ability to detect global earthquakes 

both through 24-7 analysis of earthquake 

events and through improvements in 

the Global Seismographic Network, a 

partnership with the National Science 

Foundation (NSF) and the Incorporated 

Research Institutions for Seismology. 

These changes are enabling the USGS 

to provide NOAA’s tsunami-warning 

centers with faster, more accurate estimates of earthquake location and size.

Domestic Tsunami Hazards

The USGS assesses tsunami hazards 

in the United States by investigating past 

tsunamis, identifying potential tsunami 

sources, mapping tsunami-prone coasts, 

and creating simulations of tsunami 

inundation. Emergency managers use 

this information in hazard planning and 

mitigation.

The USGS played major roles in documenting the tsunamis generated by the 

magnitude 9.2 Alaska earthquake in 1964 

and in discovering previously unknown 

tsunami hazards in Washington, Oregon, 

and California. These findings were a key 

impetus for the National Tsunami Hazard 

Mitigation Program. 

International Efforts

The USGS has teamed up with 

NOAA, the U.S. Agency for International 

Development, and other Federal agencies 

and scientific organizations to provide 

scientific information and support of 

relief efforts around the Indian Ocean.

This work builds on a rapid response 

in early 2005, when USGS geologists 

investigated tsunami effects in Sri Lanka, 

Indonesia, and the Republic of Maldives, 

and provided field training to scientists 

from Indonesia and India.

These activities are coordinated 

through the Intergovernmental Oceanographic Commission, a branch of the 

United Nations Educational, Scientific, 

and Cultural Organization. The USGS is 

particularly active in working groups that 

address seismic monitoring and hazard 

assessment.

The United States is also a member of 

the Group on Earth Observations. This 

group is committed to the development of 

a worldwide, all-hazards warning system 

as part of the integrated Global Earth 

Observation System of Systems. 

Through such efforts at home and 

abroad, the USGS helps the public, 

policymakers, and emergency managers make informed decisions on how to 

reduce losses from future tsunamis.