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Tsunami Warning Systems

Many cities around the Pacific, notably in Japan but also in Hawaii, have warning systems and evacuation procedures in the event of a serious tsunami. Tsunamis are predicted by various seismologic institutes around the world and their progress monitored by satellites.

Bottom pressure recorders with buoys as communication links are used to detect waves which would not be noticed by a human observer on deep water. The first rudimentary system to alert communities of an impending tsunami was attempted in Hawaii in the 1920s. More advanced systems were developed in the wake of the April 1, 1946 and May 23, 1960 tsunamis which caused massive devastation in Hilo, Hawaii. The United States created the Pacific Tsunami Warning Center (http://www.prh.noaa.gov/pr/ptwc/) in 1949, and linked it to an international data and warning network in 1965.

One system for providing tsunami warning is the CREST Project (Consolidated Reporting of Earthquakes and Tsunamis) implemented on the West coast (Cascadia), Alaska, and Hawaii of the United States by the USGS, NOAA, the Pacific Northwest Seismograph Network, and three other university seismic networks.

Tsunami prediction remains an imperfect science. Although the epicenter of a large underwater quake and the probable tsunami arrival times can be quickly calculated, it is almost always impossible to know whether massive underwater ground shifts have occurred, resulting in tsunami waves. As a result, false alarms are common.

The topography of the sea floor can however give a guidance on safe spots. For example, vertical disturbance on ocean bed infested with mountains are less like to lead to destructive Tsunami. This is because a possible tsunami will partially or completely collapse in the middle of the ocean if it encounters a mountain on its journey to the dry land.

No system can protect against a sudden tsunami. A devastating tsunami occurred off the coast of Hokkaido in Japan as a result of an earthquake on July 12, 1993. As a result, 202 people on the small island of Okushiri lost their lives, and hundreds more were missing or injured. This tsunami struck just three to five minutes after the quake and most victims were caught while fleeing for higher ground and secure places after surviving the earthquake.

While there remains the potential for sudden devastation from a tsunami, warning systems can be effective. For example if there were a very large subduction zone earthquake (magnitude 9.0) off the west coast of the United States, people in Japan, for example, would have a little more than 12 hours (and likely warnings from warning systems in Hawaii and elsewhere) before any tsunami arrived, giving them some time to evacuate areas likely to be affected.

External Tsunami Warning System Links

Pacific Tsunami Warning Center
Established in 1949, the Pacific Tsunami Warning Center (PTWC) in Ewa Beach, Hawai`i, provides warnings for teletsunamis to most countries in the Pacific Basin as well as to Hawai`i and all other US interests in the Pacific outside of Alaska and the US West Coast. Those areas are served by the West Coast / Alaska Tsunami Warning Center (WC/ATWC) in Palmer, Alaska. PTWC is also the warning center for Hawai`i's local and regional tsunamis

The Pacific Northwest Seismograph Network
The Pacific Northwest Seismograph Network, or PNSN, operates seismograph stations and locates earthquakes in Washington and Oregon. The network is funded by the US Geological Survey (USGS), the Department of Energy, and the State of Washington.

U.S. Geological Survey

National Oceanic and Atmospheric Administration
The National Oceanic and Atmospheric Administration (NOAA) is an agency of the United States Department of Commerce. NOAA operates a network of weather satellites, the National Weather Service, the National Hurricane Center, and cooperates with the National Ice Center.

The U.S. National Earthquake Information Center

Southern California Earthquake Data Center (http://www.data.scec.org/)
Searchable archive of earthquake data for research in seismology and earthquake engineering.


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