Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock () or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
Tsunamis are ocean waves triggered by:
Scientists do not use the term "tidal wave" because these waves are not caused by tides. Tsunami waves are unlike typical ocean waves generated by wind and storms, and most tsunamis do not "break" like the curling, wind-generated waves popular with surfers.
Tsunamis typically consist of multiple waves that rush ashore like a fast-rising tide with powerful currents. When tsunamis approach shore, they behave like a very fast moving tide that extends much farther inland than normal water. If a tsunami-causing disturbance occurs close to the coastline, a resulting tsunami can reach coastal communities within minutes. A rule of thumb is that if you see the tsunami, it is too late to outrun it. Even small tsunamis (6 feet in height, for example) are associated with extremely strong currents, capable of knocking someone off their feet. As a result of complex interactions with the coast, tsunami waves can persist for many hours.
As with many natural phenomena, tsunamis can range in size from micro-tsunamis detectable only by sensitive instruments on the ocean floor to mega-tsunamis that can affect the coastlines of entire oceans, as with the Indian Ocean tsunami of 2004. If you hear a tsunami warning or if you feel strong shaking at the coast or see very unusual wave activity (e.g., the sea withdrawing far from shore), it is important to move to high ground and stay away from the coast until wave activity has subsided (usually several hours to days).
Learn more:
Large tsunamis have occurred in the United States and will undoubtedly occur again. Significant earthquakes around the Pacific rim have generated tsunamis that struck Hawaii, Alaska, and the U.S. west coast. One of the largest and most devastating tsunamis that Hawaii has experienced was in 1946 from an earthquake along the Aleutian subduction zone. Runup heights reached a maximum of 33 to 55 feet...
NOAA (National Oceanic and Atmospheric Administration) maintains the U.S. Tsunami Warning Centers , and work in conjunction with USGS seismic networks to help determine when and where to issue tsunami warnings. Also, if an earthquake meets certain criteria for potentially generating a tsunami, the pop-up window and the event page for that earthquake on the USGS Latest Earthquakes Map will include...
Although earthquake magnitude is one factor that affects tsunami generation, there are other important factors to consider. The earthquake must be a shallow marine event that displaces the seafloor. Thrust earthquakes (as opposed to strike slip) are far more likely to generate tsunamis, but small tsunamis have occurred in a few cases from large (i.e., > M8) strike-slip earthquakes. Note the...
Although both are sea waves, a tsunami and a tidal wave are two different and unrelated phenomena. A tidal wave is a shallow water wave caused by the gravitational interactions between the Sun, Moon, and Earth ("tidal wave" was used in earlier times to describe what we now call a tsunami.) A tsunami is an ocean wave triggered by large earthquakes that occur near or under the ocean, volcanic...
A presentation on "Unusual Sources of Tsunamis From Krakatoa to Monterey Bay" by Eric Geist, USGS Research Geophysicist
- Not all tsunamis are generated by earthquakes.
- Tsunamis can be caused by volcanoes, landslides, and even atmospheric disturbances
- Data from tide gauges can help unravel the complex physics of these sources
A presentation on "Unusual Sources of Tsunamis From Krakatoa to Monterey Bay" by Eric Geist, USGS Research Geophysicist
- Not all tsunamis are generated by earthquakes.
- Tsunamis can be caused by volcanoes, landslides, and even atmospheric disturbances
- Data from tide gauges can help unravel the complex physics of these sources
How geology is reducing tsunami risk
by Bruce Jaffe, USGS Research Oceanographer
How geology is reducing tsunami risk
by Bruce Jaffe, USGS Research Oceanographer
By George Plafker, USGS Geologist Emeritus
By George Plafker, USGS Geologist Emeritus
-- Coastal Community Tsunami Hazards and Risk
By Nathan Wood, Geographer
-- Coastal Community Tsunami Hazards and Risk
By Nathan Wood, Geographer
An outcrop composed of six tsunami deposits on the inland side of the lowland backing Stardust Bay over 0.5 miles from the sea. Brown soils developed into the top of each sand sheet and black tephra (air fall volcanic ash) layers between two of the sand deposits aided correlation of the six sand sheets across the study area.
An outcrop composed of six tsunami deposits on the inland side of the lowland backing Stardust Bay over 0.5 miles from the sea. Brown soils developed into the top of each sand sheet and black tephra (air fall volcanic ash) layers between two of the sand deposits aided correlation of the six sand sheets across the study area.
The December 2004 Indian Ocean Tsunami was one of the deadliest natural disasters of modern history, killing over 225,000 people. As a result of this catastrophe, the U.S. Geological Survey has partnered with the international community to create an Indian Ocean Tsunami Warning System (IOTWS).
The December 2004 Indian Ocean Tsunami was one of the deadliest natural disasters of modern history, killing over 225,000 people. As a result of this catastrophe, the U.S. Geological Survey has partnered with the international community to create an Indian Ocean Tsunami Warning System (IOTWS).
Tsunami Preparedness explains how and why tsunamis occur, how to know that a tsunami is approaching, and what you should do. These issues are addressed by scientists, emergency managers, and first responders.
Tsunami Preparedness explains how and why tsunamis occur, how to know that a tsunami is approaching, and what you should do. These issues are addressed by scientists, emergency managers, and first responders.
Tsunamis are a constant threat to the coasts of our world. Although tsunamis are infrequent along the California coast, it is possible and necessary to prepare for potential tsunami hazards to minimize loss of life and property. Community awareness programs are important, as they strive to create an informed society by providing education and training.
Tsunamis are a constant threat to the coasts of our world. Although tsunamis are infrequent along the California coast, it is possible and necessary to prepare for potential tsunami hazards to minimize loss of life and property. Community awareness programs are important, as they strive to create an informed society by providing education and training.
Tsunamis are a constant threat to the coasts of our world. Although tsunamis are infrequent along the California coast, it is possible and necessary to prepare for potential tsunami hazards to minimize loss of life and property. Community awareness programs are important, as they strive to create an informed society by providing education and training.
Tsunamis are a constant threat to the coasts of our world. Although tsunamis are infrequent along the California coast, it is possible and necessary to prepare for potential tsunami hazards to minimize loss of life and property. Community awareness programs are important, as they strive to create an informed society by providing education and training.
Tsunamis are a constant threat to the coasts of our world. Although tsunamis are infrequent along the California coast, it is possible and necessary to prepare for potential tsunami hazards to minimize loss of life and property. Community awareness programs are important, as they strive to create an informed society by providing education and training.
Tsunamis are a constant threat to the coasts of our world. Although tsunamis are infrequent along the California coast, it is possible and necessary to prepare for potential tsunami hazards to minimize loss of life and property. Community awareness programs are important, as they strive to create an informed society by providing education and training.
The tsunami generated by the M 8.8 earthquake carried many boats onto land - in some cases hundreds of meters inland. The tsunami wave height at this location in Concepcion Harbor (Talcahuano), Chile was about 4-5 meters (12-15 feet).
The tsunami generated by the M 8.8 earthquake carried many boats onto land - in some cases hundreds of meters inland. The tsunami wave height at this location in Concepcion Harbor (Talcahuano), Chile was about 4-5 meters (12-15 feet).
Large tsunamis have occurred in the United States and will undoubtedly occur again. Significant earthquakes around the Pacific rim have generated tsunamis that struck Hawaii, Alaska, and the U.S. west coast. One of the largest and most devastating tsunamis that Hawaii has experienced was in 1946 from an earthquake along the Aleutian subduction zone. Runup heights reached a maximum of 33 to 55 feet...
NOAA (National Oceanic and Atmospheric Administration) maintains the U.S. Tsunami Warning Centers , and work in conjunction with USGS seismic networks to help determine when and where to issue tsunami warnings. Also, if an earthquake meets certain criteria for potentially generating a tsunami, the pop-up window and the event page for that earthquake on the USGS Latest Earthquakes Map will include...
Although earthquake magnitude is one factor that affects tsunami generation, there are other important factors to consider. The earthquake must be a shallow marine event that displaces the seafloor. Thrust earthquakes (as opposed to strike slip) are far more likely to generate tsunamis, but small tsunamis have occurred in a few cases from large (i.e., > M8) strike-slip earthquakes. Note the...
Although both are sea waves, a tsunami and a tidal wave are two different and unrelated phenomena. A tidal wave is a shallow water wave caused by the gravitational interactions between the Sun, Moon, and Earth ("tidal wave" was used in earlier times to describe what we now call a tsunami.) A tsunami is an ocean wave triggered by large earthquakes that occur near or under the ocean, volcanic...
A presentation on "Unusual Sources of Tsunamis From Krakatoa to Monterey Bay" by Eric Geist, USGS Research Geophysicist
- Not all tsunamis are generated by earthquakes.
- Tsunamis can be caused by volcanoes, landslides, and even atmospheric disturbances
- Data from tide gauges can help unravel the complex physics of these sources
A presentation on "Unusual Sources of Tsunamis From Krakatoa to Monterey Bay" by Eric Geist, USGS Research Geophysicist
- Not all tsunamis are generated by earthquakes.
- Tsunamis can be caused by volcanoes, landslides, and even atmospheric disturbances
- Data from tide gauges can help unravel the complex physics of these sources
How geology is reducing tsunami risk
by Bruce Jaffe, USGS Research Oceanographer
How geology is reducing tsunami risk
by Bruce Jaffe, USGS Research Oceanographer
By George Plafker, USGS Geologist Emeritus
By George Plafker, USGS Geologist Emeritus
-- Coastal Community Tsunami Hazards and Risk
By Nathan Wood, Geographer
-- Coastal Community Tsunami Hazards and Risk
By Nathan Wood, Geographer
An outcrop composed of six tsunami deposits on the inland side of the lowland backing Stardust Bay over 0.5 miles from the sea. Brown soils developed into the top of each sand sheet and black tephra (air fall volcanic ash) layers between two of the sand deposits aided correlation of the six sand sheets across the study area.
An outcrop composed of six tsunami deposits on the inland side of the lowland backing Stardust Bay over 0.5 miles from the sea. Brown soils developed into the top of each sand sheet and black tephra (air fall volcanic ash) layers between two of the sand deposits aided correlation of the six sand sheets across the study area.
The December 2004 Indian Ocean Tsunami was one of the deadliest natural disasters of modern history, killing over 225,000 people. As a result of this catastrophe, the U.S. Geological Survey has partnered with the international community to create an Indian Ocean Tsunami Warning System (IOTWS).
The December 2004 Indian Ocean Tsunami was one of the deadliest natural disasters of modern history, killing over 225,000 people. As a result of this catastrophe, the U.S. Geological Survey has partnered with the international community to create an Indian Ocean Tsunami Warning System (IOTWS).
Tsunami Preparedness explains how and why tsunamis occur, how to know that a tsunami is approaching, and what you should do. These issues are addressed by scientists, emergency managers, and first responders.
Tsunami Preparedness explains how and why tsunamis occur, how to know that a tsunami is approaching, and what you should do. These issues are addressed by scientists, emergency managers, and first responders.
Tsunamis are a constant threat to the coasts of our world. Although tsunamis are infrequent along the California coast, it is possible and necessary to prepare for potential tsunami hazards to minimize loss of life and property. Community awareness programs are important, as they strive to create an informed society by providing education and training.
Tsunamis are a constant threat to the coasts of our world. Although tsunamis are infrequent along the California coast, it is possible and necessary to prepare for potential tsunami hazards to minimize loss of life and property. Community awareness programs are important, as they strive to create an informed society by providing education and training.
Tsunamis are a constant threat to the coasts of our world. Although tsunamis are infrequent along the California coast, it is possible and necessary to prepare for potential tsunami hazards to minimize loss of life and property. Community awareness programs are important, as they strive to create an informed society by providing education and training.
Tsunamis are a constant threat to the coasts of our world. Although tsunamis are infrequent along the California coast, it is possible and necessary to prepare for potential tsunami hazards to minimize loss of life and property. Community awareness programs are important, as they strive to create an informed society by providing education and training.
Tsunamis are a constant threat to the coasts of our world. Although tsunamis are infrequent along the California coast, it is possible and necessary to prepare for potential tsunami hazards to minimize loss of life and property. Community awareness programs are important, as they strive to create an informed society by providing education and training.
Tsunamis are a constant threat to the coasts of our world. Although tsunamis are infrequent along the California coast, it is possible and necessary to prepare for potential tsunami hazards to minimize loss of life and property. Community awareness programs are important, as they strive to create an informed society by providing education and training.
The tsunami generated by the M 8.8 earthquake carried many boats onto land - in some cases hundreds of meters inland. The tsunami wave height at this location in Concepcion Harbor (Talcahuano), Chile was about 4-5 meters (12-15 feet).
The tsunami generated by the M 8.8 earthquake carried many boats onto land - in some cases hundreds of meters inland. The tsunami wave height at this location in Concepcion Harbor (Talcahuano), Chile was about 4-5 meters (12-15 feet).
