Tsunami Evacuation Route Sign
What is it about an earthquake that causes a tsunami?
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 following are general guidelines based on historical observations and in accordance with procedures of NOAA's Pacific Tsunami Warning Center.
Magnitudes below 6.5
Earthquakes of this magnitude are very unlikely to trigger a tsunami.
Magnitudes between 6.5 and 7.5
Earthquakes of this size do not usually produce destructive tsunamis. However, small sea level changes might be observed in the vicinity of the epicenter. Tsunamis capable of producing damage or casualties are rare in this magnitude range but have occurred due to secondary effects such as landslides or submarine slumps.
Magnitudes between 7.6 and 7.8
Earthquakes of this size might produce destructive tsunamis, especially near the epicenter. At greater distances, small sea level changes might be observed. Tsunamis capable of producing damage at great distances are rare in the magnitude range.
Magnitude 7.9 and greater
Destructive local tsunamis are possible near the epicenter, and significant sea level changes and damage might occur in a broader region. Note that with a magnitude 9.0 earthquake, there is a possibility of an aftershock of magnitude 7.5 or greater.
Learn more:
Related
Could a large tsunami happen in the United States? Could a large tsunami happen in the United States?
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...
Is there a system to warn populations of an imminent occurrence of a tsunami? Is there a system to warn populations of an imminent occurrence of a tsunami?
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 a...
What are tsunamis? What are tsunamis?
Tsunamis are ocean waves triggered by: Large earthquakes that occur near or under the ocean Volcanic eruptions Submarine landslides Onshore landslides in which large volumes of debris fall into the water 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"...
What is the difference between a tsunami and a tidal wave? What is the difference between a tsunami and a tidal wave?
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...
Tsunami Evacuation Route Sign
PubTalk 1/2017 — Unusual sources of tsunamis
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
PubTalk 7/2015 — The Giant Cascadia Earthquake of January 26, 1700
Detective Stories from North America and Japan
by Brian Atwater, USGS Seattle
Detective Stories from North America and Japan
by Brian Atwater, USGS Seattle
PubTalk 12/2014 — Ten Years After the 2004 Indian Ocean Tsunami
How geology is reducing tsunami risk
by Bruce Jaffe, USGS Research Oceanographer
How geology is reducing tsunami risk
by Bruce Jaffe, USGS Research Oceanographer
PubTalk 2/2014 — 1964 Great Alaska Earthquake and Tsunami 50th Anniv.
By George Plafker, USGS Geologist Emeritus
By George Plafker, USGS Geologist Emeritus
Terms to describe the measurement of tsunamis
Bathymetry—the measurement of water depth of a body of water (e.g., ocean, sea, river, bay, lake, etc.)
Bathymetry—the measurement of water depth of a body of water (e.g., ocean, sea, river, bay, lake, etc.)
Tsunamis: Tides have nothing to do with it
Tsunamis are devastating. Usually associated with earthquakes in the Pacific, these giant surges of oceanic water can kill thousands and do billions of dollars of damage in minutes. Surprisingly, most people in Oregon are not aware of the tsunami history and hazard along our very own coast.
Tsunamis are devastating. Usually associated with earthquakes in the Pacific, these giant surges of oceanic water can kill thousands and do billions of dollars of damage in minutes. Surprisingly, most people in Oregon are not aware of the tsunami history and hazard along our very own coast.
Tsunami Preparedness along the West Coast, USA
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.
Tsunami Preparedness in Northern California, USA
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.
Tsunami Preparedness in Southern California, USA
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.
Tsunami Preparedness in Central California, USA
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.
Heavily damaged home in Banda Aceh, Sumatra from the 2004 tsunami
A severely damaged home, or a portion of one, sits atop debris in Banda Aceh on the island of Sumatra. Damage was caused by a massive, highly destructive tsunami, triggered by a magnitude 9.1 earthquake just offshore of Sumatra, on December 26, 2004.
A severely damaged home, or a portion of one, sits atop debris in Banda Aceh on the island of Sumatra. Damage was caused by a massive, highly destructive tsunami, triggered by a magnitude 9.1 earthquake just offshore of Sumatra, on December 26, 2004.
Earthquake starts tsunami
An earthquake along a subduction zone happens when the leading edge of the overriding plate breaks free and springs seaward, raising the sea floor and the water above it. This uplift starts a tsunami. Meanwhile, the bulge behind the leading edge collapses, thinning the plate and lowering coastal areas.
An earthquake along a subduction zone happens when the leading edge of the overriding plate breaks free and springs seaward, raising the sea floor and the water above it. This uplift starts a tsunami. Meanwhile, the bulge behind the leading edge collapses, thinning the plate and lowering coastal areas.
Related
Could a large tsunami happen in the United States? Could a large tsunami happen in the United States?
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...
Is there a system to warn populations of an imminent occurrence of a tsunami? Is there a system to warn populations of an imminent occurrence of a tsunami?
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 a...
What are tsunamis? What are tsunamis?
Tsunamis are ocean waves triggered by: Large earthquakes that occur near or under the ocean Volcanic eruptions Submarine landslides Onshore landslides in which large volumes of debris fall into the water 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"...
What is the difference between a tsunami and a tidal wave? What is the difference between a tsunami and a tidal wave?
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...
Tsunami Evacuation Route Sign
Tsunami Evacuation Route Sign
PubTalk 1/2017 — Unusual sources of tsunamis
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
PubTalk 7/2015 — The Giant Cascadia Earthquake of January 26, 1700
Detective Stories from North America and Japan
by Brian Atwater, USGS Seattle
Detective Stories from North America and Japan
by Brian Atwater, USGS Seattle
PubTalk 12/2014 — Ten Years After the 2004 Indian Ocean Tsunami
How geology is reducing tsunami risk
by Bruce Jaffe, USGS Research Oceanographer
How geology is reducing tsunami risk
by Bruce Jaffe, USGS Research Oceanographer
PubTalk 2/2014 — 1964 Great Alaska Earthquake and Tsunami 50th Anniv.
By George Plafker, USGS Geologist Emeritus
By George Plafker, USGS Geologist Emeritus
Terms to describe the measurement of tsunamis
Bathymetry—the measurement of water depth of a body of water (e.g., ocean, sea, river, bay, lake, etc.)
Bathymetry—the measurement of water depth of a body of water (e.g., ocean, sea, river, bay, lake, etc.)
Tsunamis: Tides have nothing to do with it
Tsunamis are devastating. Usually associated with earthquakes in the Pacific, these giant surges of oceanic water can kill thousands and do billions of dollars of damage in minutes. Surprisingly, most people in Oregon are not aware of the tsunami history and hazard along our very own coast.
Tsunamis are devastating. Usually associated with earthquakes in the Pacific, these giant surges of oceanic water can kill thousands and do billions of dollars of damage in minutes. Surprisingly, most people in Oregon are not aware of the tsunami history and hazard along our very own coast.
Tsunami Preparedness along the West Coast, USA
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.
Tsunami Preparedness in Northern California, USA
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.
Tsunami Preparedness in Southern California, USA
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.
Tsunami Preparedness in Central California, USA
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.
Heavily damaged home in Banda Aceh, Sumatra from the 2004 tsunami
A severely damaged home, or a portion of one, sits atop debris in Banda Aceh on the island of Sumatra. Damage was caused by a massive, highly destructive tsunami, triggered by a magnitude 9.1 earthquake just offshore of Sumatra, on December 26, 2004.
A severely damaged home, or a portion of one, sits atop debris in Banda Aceh on the island of Sumatra. Damage was caused by a massive, highly destructive tsunami, triggered by a magnitude 9.1 earthquake just offshore of Sumatra, on December 26, 2004.
Earthquake starts tsunami
An earthquake along a subduction zone happens when the leading edge of the overriding plate breaks free and springs seaward, raising the sea floor and the water above it. This uplift starts a tsunami. Meanwhile, the bulge behind the leading edge collapses, thinning the plate and lowering coastal areas.
An earthquake along a subduction zone happens when the leading edge of the overriding plate breaks free and springs seaward, raising the sea floor and the water above it. This uplift starts a tsunami. Meanwhile, the bulge behind the leading edge collapses, thinning the plate and lowering coastal areas.
Updated Date: May 9, 2025