Discover where, when and how severely tsunamis affected Earth in geologic history. Information regarding Tsunami Deposits and Proxies for Tsunami Events complements the historical records currently available through the Global Tsunami Database.

Tsunami is a Japanese word meaning harbor wave. It is a water wave or a series of waves generated by an impulsive vertical displacement of the surface of the ocean or other body of water. This slide set depicts advancing waves, harbor damage, and structural damage from seven tsunami events which have occurred since 1946 in the Pacific region. The set includes before-and-after views of Scotch Cap Lighthouse (the Aleutian Islands).Tsunami is a Japanese word meaning "harbor wave." It is a water wave or a series of waves generated by an impulsive vertical displacement of the surface of the ocean or other body of water. Tsunamis are commonly called seismic sea waves or incorrectly, tidal waves. The term "tidal wave" is frequently used in the older literature and in popular accounts, but is now considered incorrect. Tides are produced by the rotational attraction of the sun and moon and occur predictably, with twelve hour periods. The effects of a tsunami may be increased or decreased depending on the level of the tide, but otherwise the two phenomena are independent.Major tsunamis occur in the Pacific Ocean region only about once per decade. These major events, such as that in Prince William Sound, Alaska, in March 1964, and the tsunami generated off the coast of Chile in 1960, have been devastating over large distances. Tsunamis have been responsible for thousands of fatalities, especially in Japan and Indonesia.Most tsunamis are caused by a rapid vertical movement along a break in Earth's crust (i.e., their origin is tectonic). A tsunami is generated when a large mass of earth on the bottom of the ocean drops or rises, thereby displacing the column of water directly above it. This type of displacement commonly occurs in large subduction zones, where the collision of two tectonic plates causes the oceanic plate to dip beneath the continental plate to form deep ocean trenches. Shallow tsunamigenic earthquakes occur offshore in these trenches. Subduction occurs along most of the island arcs and coastal areas of the Pacific, except for the west coast of the United States and Canada. Such trench areas off continental coasts and island arcs are generating areas for major tsunamis affecting the entire Pacific Basin.Volcanic eruptions have also generated significant tsunamis, resulting in death tolls as high as 30,000 people from a single event, as in the Krakatoa eruption of 1883. Tsunamis effectively transmit energy to areas outside the reach of the volcanic eruption itself. The most efficient methods of tsunami generation by volcanoes include disruption of a body of water by the collapse of all or part of the volcanic edifice, subsidence, an explosion, a landslide, a glowing avalanche, and an earthquake accompanying or preceding the eruption. Roughly one-half of all volcanic tsunamis are generated at calderas or at cones within calderas. Submarine eruptions may also cause minor tsunamis.The largest tsunamis are caused by meteorite impact in ocean basins. While there have been none recorded in historical times, tsunamis from the Chixulub, Yucatan, crater (66 million years b.p.) were up to 5 km high. Tsunami deposits have been found in west Texas nearly 1,000 kilometers inland. Modelling shows that a moderate size meteor impact in the Atlantic Ocean would have devastating results along the entire Atlantic seaboard of the United States. Such impacts are expected on an average of once in about 15,000 years.Subaerial and submarine landslides into bays or lakes have generated locally destructive tsunamis. Other possible but less efficient methods of tsunami generation also exist. More than one mechanism commonly is involved in the generation of a tsunami including vertical movement of the crust by a seismic impulse (an earthquake) or a submarine landslide.Tsunamis have been reported since ancient times. They have been documented extensively, especially in Japan and the Mediterranean areas. One of the first recorded tsunamis may have

The Significant Earthquake Database is a global listing of over 5,700 earthquakes from 2150 BC to the present. A significant earthquake is classified as one that meets at least one of the following criteria: caused deaths, caused moderate damage (approximately $1 million or more), magnitude 7.5 or greater, Modified Mercalli Intensity (MMI) X or greater, or the earthquake generated a tsunami. The database provides information on the date and time of occurrence, latitude and longitude, focal depth, magnitude, maximum MMI intensity, and socio-economic data such as the total number of casualties, injuries, houses destroyed, and houses damaged, and $ dollage damage estimates. References, political geography, and additional comments are also provided for each earthquake. If the earthquake was associated with a tsunami or volcanic eruption, it is flagged and linked to the related tsunami event or significant volcanic eruption.

These water level data were digitized from a scanned marigram image associated with the tsunami event of 1945-11-27 at a tide gauge located at Karachi, Pakistan, and referenced to station datum. The Karachi marigram is one of the two instrumental records existing of the 1945 Makran tsunami and spans most of the 16 days between November 15 and December 1. The original Karachi analog record belongs to the Survey of India (SOI) and was collected and digitized by the National Institute of Oceanography (NIO) and Indian National Center for Ocean Information Services (INCOIS) for use in the publication of a few scientific papers. This digital marigram scan was reformatted into the accompanying digital, numerical time series by the Cooperative Institute for Research in Environmental Sciences (CIRES), Boulder, CO. Acknowledgement of SOI, NIO, and INCOIS should be included in any future scientific works using this record.

The tsunami generated by a magnitude 7.9 (Mw) earthquake destroyed 700 boats and 59 houses for a total of $800 million in property damage in Japan (1983 dollars). One hundred and four people drowned in Japan and three drowned in Korea.

The March 11 earthquake generated a devastating tsunami that was observed all over the Pacific and caused tremendous devastation locally, including an accident at the Fukushima Daiichi Nuclear Power Plant.

Two earthquakes occurred in the morning on Hawaii Island. The first earthquake (3 hours 36 minutes local time, 5.1 Ms, epicenter near the Kilauea crater) awakened the entire population of the island. The second earthquake (4 hours 48 minutes local time, 7.2 Ms, off the southeast coast) caused damage (IX) at Hilo and damage (VIII) at Hawaii Volcanoes National Park. In many places houses were severely damaged, roads were breached and became unusable due to landslides; electric power lines were broken. Maximum subsidence 3.5 meters along the southeast coast. Maximum width of ground cracks 1 meter in the park. There was a brief eruption of the Kilauea Volcano. The second earthquake generated a locally damaging submarine landslide tsunami that was recorded at tide gauge stations in Alaska, California, Galapagos Islands, Peru, and Chile.

CO-OPS has been involved with tsunami warning and mitigation since the Coast and Geodetic Survey started the Tsunami Warning System in 1948 to provide warnings to the Hawaiian Islands. After the December 2004 Indian Ocean tsunami, CO-OPS was tasked to coordinate with the NOAA Tsunami Warning Centers in upgrading existing stations with new Data Collection Platform (DCP) and communications technology and with expanding the tsunami warning capabilities of the National Water Level Observation Network (NWLON). Work began in 2005 to upgrade 33 existing water level stations and install 16 new stations from the Pacific Ocean to the Caribbean Sea by October 2006. As of September 2006, all 33 upgrades are complete, as well as 15 of the 16 new installations. As of October 2006, the NWLON consist of 196 long-term water level stations along all U.S. coasts, including the Great Lakes, Alaska, Hawaii, the Pacific Ocean Island Territories, Puerto Rico, and the U.S. Virgin Islands. The NOAA National Centers for Environmental Information (formerly National Geophysical Data Center) serves as the archive center for these data and provides the historical data to users.

CO-OPS has been involved with tsunami warning and mitigation since the Coast and Geodetic Survey started the Tsunami Warning System in 1948 to provide warnings to the Hawaiian Islands. After the December 2004 Indian Ocean tsunami, CO-OPS was tasked to coordinate with the NOAA Tsunami Warning Centers in upgrading existing stations with new Data Collection Platform (DCP) and communications technology and with expanding the tsunami warning capabilities of the National Water Level Observation Network (NWLON). Work began in 2005 to upgrade 33 existing water level stations and install 16 new stations from the Pacific Ocean to the Caribbean Sea by October 2006. As of September 2006, all 33 upgrades are complete, as well as 15 of the 16 new installations. As of October 2006, the NWLON consist of 196 long-term water level stations along all U.S. coasts, including the Great Lakes, Alaska, Hawaii, the Pacific Ocean Island Territories, Puerto Rico, and the U.S. Virgin Islands. The NOAA National Centers for Environmental Information (formerly National Geophysical Data Center) serves as the archive center for these data and provides the historical data to users.

CO-OPS has been involved with tsunami warning and mitigation since the Coast and Geodetic Survey started the Tsunami Warning System in 1948 to provide warnings to the Hawaiian Islands. After the December 2004 Indian Ocean tsunami, CO-OPS was tasked to coordinate with the NOAA Tsunami Warning Centers in upgrading existing stations with new Data Collection Platform (DCP) and communications technology and with expanding the tsunami warning capabilities of the National Water Level Observation Network (NWLON). Work began in 2005 to upgrade 33 existing water level stations and install 16 new stations from the Pacific Ocean to the Caribbean Sea by October 2006. As of September 2006, all 33 upgrades are complete, as well as 15 of the 16 new installations. As of October 2006, the NWLON consist of 196 long-term water level stations along all U.S. coasts, including the Great Lakes, Alaska, Hawaii, the Pacific Ocean Island Territories, Puerto Rico, and the U.S. Virgin Islands. The NOAA National Centers for Environmental Information (formerly National Geophysical Data Center) serves as the archive center for these data and provides the historical data to users.