Tsunamis

Tsunamis have hit Washington in the past, and they will happen again in the future. Click below to learn about how and where tsunamis occur, how to recognize a tsunami, how to evacuate before a tsunami arrives, and what geologists at the Washington Geological Survey are doing to learn more about these natural hazards.

Understanding Tsunamis

In order to prepare for tsunamis we must first understand them. Knowing how tsunamis form, how they travel to reach shorelines, and how they behave once they are onshore gives us an idea of where they pose the greatest hazard.

What is a Tsunami

A tsunami is a powerful and destructive natural force. It’s a series of extremely long waves caused when an event, such as an earthquake, suddenly shifts water in the ocean or in a lake. A tsunami radiates outward in all directions from its source and can move across entire oceans in less than a day.

The speed of a tsunami depends on the depth of the water it’s traveling through. The deeper the water, the faster the tsunami. In the deep ocean, tsunamis are barely noticeable, but they can move as fast as a jet plane, at a speed of more than 500 mph. As they enter shallow water near land, they slow to approximately 20 or 30 mph, which is still faster than a person can run.

As tsunamis slow down, they grow in height. When they arrive on shore, most are less than 10 feet high. In extreme cases, however, they can exceed 100 feet when they strike near their source. Large tsunamis can flood low-lying coastal areas more than a mile inland.

Not all tsunamis act the same. A small nondestructive tsunami in one place may be very large and violent a few miles away. This is because coastal areas have different beach slopes and different offshore and coastal geographical features, such as reefs, bays, and river mouths.

Unlike common wind waves, tsunami waves have a long wavelength of many tens of miles. This makes tsunamis far more powerful. Wind waves, due to their short wavelength, often break onto the shore early and are highly turbulent. They generally do not travel very far inland.

Tsunami waves approach the shore as a rapidly rising flow or wall of water. A tsunami will not look like a normal wind wave. Sometimes, the bottom of the wave, the trough, will arrive first. When this happens, the water suddenly draws back, showing the ocean floor, reefs, and fish, like a very low, low tide.

A tsunami event may consist of many waves. The first tsunami wave may not be the largest, as shown in the video below. In many parts of Japan during the 2011 Tohoku tsunami, the fifth wave was the largest. In the 1964 Alaska earthquake, the fourth wave was the largest to strike Crescent City. The time between waves can range from 5 minutes to 2 hours. Dangerous coastal flooding and powerful currents may last for several hours or days. Evacuees should remain in a safe high ground location and not return to low-lying areas until directed to do so by emergency management.

Seiches

A seiche is a standing wave that can form in enclosed bodies of water such as lakes, bays, and even swimming pools. When seismic waves shift shorelines during an earthquake, this movement pushes the water toward one side of the basin. The water then begins to slosh back and forth. This type of wave has been particularly damaging for inland lakes such as Lake Union, and could occur in areas around the Puget Sound.

What Causes Tsunamis

The most common cause of a tsunami is a large earthquake under the ocean floor. Landslides, volcanic activity, certain weather conditions, and falling space objects, such as meteorites can also generate tsunamis. Most of the tsunamis (88%) in the Global Historical Tsunami Database were generated by earthquakes or landslides caused by earthquakes.

Earthquakes

Not all earthquakes generate tsunamis. Whether an earthquake generates a tsunami or not depends on key characteristics like the location, magnitude, and depth of the earthquake. In general, earthquakes that generate tsunamis:

• Occur under the ocean or near shorelines (usually at or near subduction zones, where oceanic and continental plates collide).
• Have magnitudes of more than 7.0 (usually, an earthquake must exceed magnitude 8.0 to generate a dangerous distant tsunami).
• Are triggered less than 100 kilometers (62 miles) below Earth’s surface.

As these details are generally not known immediately following an earthquake, you should always evacuate from coastal areas when any strong shaking is felt. For more information about earthquakes, check out our Earthquakes and Faults webpage.

Earthquake Sources

Washington has three major earthquake sources that have the potential to cause tsunamis: subduction zone earthquakes, deep (Benioff Zone) earthquakes, and shallow crustal fault earthquakes.

Cascadia Subduction Zone Earthquakes

The Cascadia subduction zone off the coast of Washington, British Columbia, Oregon, and northern California is the most significant source of tsunami hazard for Washington State. This very large fault can generate large and damaging earthquakes and tsunamis. The following diagrams show how tsunamis are created along the Cascadia subduction zone.

Crustal Faults

Other faults in Washington, such as the Seattle Fault, can also move the ocean floor and cause tsunamis. The Seattle Fault is known to have had an earthquake event that directly produced a tsunami (see Black and others, 2023), and other crustal faults (Tacoma Fault and Darrington-Devils Mountain fault zone, for example) could produce tsunamis (Williams and others, 2000).

Additionally, numerous deposits from landslide-generated tsunamis that were triggered by local earthquakes are found throughout Puget Sound. For this reason we consider all active crustal faults that are near Puget Sound to be a possible direct or indirect source of future tsunamis. Models for tsunami inundation in parts of Puget Sound exist for a Seattle Fault earthquake derived tsunami and can be found on our Geologic Information Portal.

Distant Events

Tsunamis generated from earthquakes at other subduction zones and faults or volcanoes around the Pacific Ocean have the potential to impact our shores. Of the numerous historical events that have occurred, only the 1964 Alaska earthquake-generated tsunami has caused damage to the Washington coast. Most tsunami alert messages received for Washington are related to earthquakes in Alaska. You can read more about the impacts of the 1964 Alaska tsunami here.

Landslides

Tsunamis can be generated when a landslide displaces water. Rock falls, slope failures, debris flows, and slumps are all types of landslides. Icefalls, avalanches, and glacial calving (the breaking off of large pieces of ice from a glacier) can also cause tsunamis.

Whether a tsunami is created depends on the amount of landslide material, the speed at which the material is moving, and the depth the material reaches. Near its source, a landslide-generated tsunami may be larger than a tsunami generated by an earthquake, and it can affect nearby coasts within minutes with little to no warning. These tsunamis usually lose energy quickly and rarely affect distant coasts.

Volcanic Eruptions

When volcanoes erupt under water or near shorelines, the eruption can displace water, causing a tsunami. Like landslide-generated tsunamis, tsunamis generated by volcanic activity usually lose energy quickly and rarely affect distant coasts. Several types of volcanic activity can displace enough water to generate destructive tsunamis:

• Pyroclastic flows (flowing mixtures of rock fragments, gas, and ash).
• Submarine eruptions near the ocean surface.
• Landslides (such as the collapse of the flank of a volcano).
• Lateral blasts (sideways eruptions).

The latest eruption of Hunga Tonga-Hunga Ha'apai volcano on January 15, 2022, is the most recent volcanogenic tsunami.

Oregon State University maintains a list of noteworthy tsunamis triggered by volcanoes.

Bolide (Meteorite) Impacts

If large objects from space hit Earth, they can displace water and cause a tsunami. To date, no asteroid impact-generated tsunamis have been recorded during historical times. There is evidence that such events may have happened in the geologic past. The most well-known example is the Chicxulub impact 65 million years ago.

Weather

Tsunamis can even be caused by weather changes. Air pressure disturbances often associated with fast-moving weather systems, like lines of active thunderstorms, can generate tsunamis. Their development depends on the intensity, direction, and speed of the air pressure disturbance as it travels over a water body. Also, in extremely rare cases, an air pressure wave generated by a volcanic eruption can trigger meteotsunamis, as happened in the Tonga 2022 eruption.

Most meteotsunamis are too small to notice, but large meteotsunamis can bring dangerous waves, flooding, and strong currents that can cause damage, injuries, and deaths. Meteotsunamis are also regional, meaning they don’t affect entire coastlines or bodies of water.

The deadliest known meteotsunami on record occurred on June 26, 1954, on Lake Michigan, Illinois when an approximately 15-foot wave fatally swept seven people off a pier.

Local and Distant Tsunamis

The difference between a local and distant tsunami is the distance between a tsunami’s source (where the tsunami originated) and where the wave may strike land. This affects how long it takes for the wave to arrive.

A local tsunami, also called a local-source or near-field tsunami, is from a nearby source and may arrive in less than 1 hour, sometimes in just minutes. Local tsunamis pose the greatest threat because tsunamis are most damaging near their source and there is little time to issue official warnings and evacuate.

The public must know how to recognize and respond to natural tsunami warnings, such as ground shaking from an earthquake. Examples of local tsunami threats in Washington are tsunamis generated from earthquake events on the Cascadia subduction zone or local crustal faults such as the Seattle or Tacoma faults. They may also be generated by landslides, either above or below the water.

A distant tsunami, also called a distant-source tsunami, a far-field tsunami, or a tele-tsunami, is from a faraway source, sometimes on the other side of the ocean. This means there is more time to issue and respond to official warnings (usually at least three hours). Examples of distant-source threats in Washington are tsunamis generated from earthquake events on the Alaska-Aleutian Subduction Zone.

Tsunamis in Washington

If you’ve been to beaches and coastal communities in the Pacific Northwest, you’ve probably seen signs like these

These signs tell you that you are in a place that is especially at risk for tsunamis. Washington has the second highest seismic risk in the United States (behind California) due to the presence of numerous crustal faults and a subduction zone offshore.

There are four main types of tsunami risk in Washington. Each type affects different parts of the state. Emergency planners and hazard geologists are working hard to learn more about these risks.

Types of tsunami risk
Type of tsunami	Description	Area of greatest impact	Time to evacuate
Distant	A tsunami is created by a distant earthquake or landslide and travels across the ocean	Pacific coastal communities	Hours
Cascadia subduction zone	Tsunami created by large magnitude 8–9 earthquake off the Washington, Oregon, or British Columbia coasts	Pacific coastal communities	Tens of minutes
Local earthquake (for example, the Seattle Fault)	Tsunami created in large body of water from an earthquake on local faults	Communities close to the body of water	Minutes to tens of minutes
Landslide-caused tsunami	Large landslide occurs underwater or slides from land into water	Communities close to the landslide	Minutes to tens of minutes

Evidence of Past Earthquakes and Tsunamis

For an earthquake to produce a tsunami, a rapid, large change in the elevation of the ocean floor must occur. These land-level changes are known as uplift if the Earth’s surface rises and subsidence if the Earth’s surface falls. Some local examples of land level change are Restoration Point in Seattle, where the 923-924 AD Seattle Fault earthquake uplifted the land surface by 23 feet (Bucknam and others, 1992, Black and others, 2023).

There are also “ghost forests” on the outer coasts of Washington and Oregon. These forests represent locations where trees were killed when the land suddenly dropped during a major earthquake, submerging their roots in saltwater. Tree ring dating, or dendrochronology, places the death of these trees in the winter of 1699–1700, the same time that the last Cascadia subduction zone earthquake occurred.

When tsunamis inundate a coastline, they may leave behind distinct sediment deposits. These deposits are typically layers of sand and other debris that are carried up and deposited on land by the force of the tsunami waves. These deposits are found in marshes and near-tidal areas where the sand gets trapped in the root systems of plants. The thicknesses of these deposits reflect the size of the tsunami and the probable tsunami source.

2024 Lake Roosevelt Landslide and Tsunami 

On November 17, 2024, a pair of landslides, together forming a single larger landslide complex, occurred on the west bank of Lake Roosevelt near Kettle Falls. The landslides generated tsunamis within Lake Roosevelt that impacted shoreline areas within 2–3 mi of the slides.

Department of Natural Resources geologists deployed to the site of the landslide and tsunami shortly after it occurred to document impacts and investigate what happened. The Washington Geological Survey also published a Quick Report summarizing their findings:

• Quick Report 2025-01: Reconnaissance investigation of the November 17, 2024, Lake Roosevelt landslide and tsunami, Stevens and Ferry Counties, Washington (Pamphlet, 5.3 MB)
• Data Supplement to Quick Report 2025-01 (2.9 GB zip file)

This is just the latest event in the long history of tsunamigenic landslides generated on the lake near Kettle Falls and in other parts of Lake Roosevelt. This indicates that portions of lake shores are geologically unstable and may have future landslides and tsunamis triggered on them.

What We Do

The mission of the Washington Geological Survey is to collect, develop, use, distribute, and preserve geologic information to promote the safety, health, and welfare of the people of Washington, protect the environment, and support the economy. To do this, WGS collaborates with the National Oceanic and Atmospheric Administration (NOAA), the University of Washington, and other partners to model the inundation (flooding) of coastal areas from tsunamis.

Tsunami Inundation Mapping

In order to prepare for tsunami hazards, it is important to have a sense of which areas will be inundated if a tsunami arrives. The extent of inundation is highly dependent on the source of the tsunami and the distance from the source to the affected area. Since earthquake-triggered tsunamis are more likely to impact large areas, most models simulate tsunamis generated by a variety of different possible earthquake scenarios. A mathematical simulation using high-speed computers then models how long it could take for tsunami waves to arrive (arrival time), which areas might be impacted (inundation extent), how deep the water could be (flow depth), and how quickly waters could be moving (current speed).

Evacuation Maps and Supporting Products

When a tsunami happens, it is critically important to know where to go and how long it will take to get there. This gives individuals and communities the highest chance of surviving the tsunami. The Survey works with the Washington Emergency Management Division and local, county, tribal, and other planners and emergency managers to develop, publish, and distribute evacuation maps. For example, one type of map produced by WGS shows how many minutes it would take to evacuate on foot from within the tsunami inundation zone. These maps are made for areas that are especially at risk of damaging tsunamis. Read more under the Tsunami Evacuation Maps section.

Outreach

We collaborate with a wide range of partners to enhance knowledge of tsunami hazards. By working alongside schools, universities, geoscience professionals, organizations, and communities, we aim to build a more disaster-resilient society. In addition, we provide a comprehensive collection of resources on tsunamis, including this webpage, our tsunami hazards booklet, and our tsunami modeling fact sheet.

Emergency Response

In the event of a tsunami alert for Washington State, the Washington Geological Survey’s Tsunami Program geologists are tasked with responding to the State Emergency Operations Center and providing scientific expertise to state, county, city, and tribal emergency managers. We coordinate with the scientists and staff at the National Tsunami Warning Center and National Weather Service to understand the situation and ensure that emergency managers and the public have the information necessary to make informed decisions.

WGS may activate the Washington Geologic Hazards Clearinghouse following a tsunami event where people are injured or infrastructure is damaged or threatened. The aim of the Clearinghouse is to provide emergency responders and interested parties with prompt information on the impacts of a significant geologic hazard event, and to collect perishable geologic information about the event that can improve understanding of future hazards.

Preparation and Evacuation

It is important to know the warning signs of a tsunami. Know what to expect. Know what to do. Be familiar with your local evacuation routes and areas of high ground as indicated on our evacuation maps.

For people in Washington, the single biggest warning of a potential tsunami is a large earthquake.

If you are near the ocean or in Puget Sound when there is a large earthquake or there is a tsunami warning, EVACUATE TO HIGHER GROUND!

Be aware that a tsunami may be coming if you:

• Hear a tsunami warning siren or receive a tsunami alert.
• Feel a strong earthquake near the ocean or a large lake. A strong earthquake is one that knocks people down, damages buildings, or lasts for longer than 20 seconds.
• Notice a very large wave approaching.
• See coastal waters recede. As the tsunami approaches, sometimes sea level will drop rapidly as the wave gets taller.
• Notice an unusually rapid rise in sea level. Some tsunamis will have a surge in front of them as they approach land. These surges can be very damaging and dangerous.
• Notice a landslide that falls or slides into the ocean, a large lake, or a river.

If you notice any of these signs or hear a tsunami warning, EVACUATE IMMEDIATELY!

For more information about tsunami warning signs check out these websites:

• U.S. Tsunami Warning System
• National Tsunami Hazard Mitigation Program
• Ready.gov Tsunami Page
• Washington Emergency Management Tsunami Page

Preparation

These are some steps you can take right now to ensure you are 'prepared, not scared' when it comes to the possibility of a tsunami. 

• Ensure you have multiple ways to receive warnings. Get a battery-operated NOAA Weather Radio, sign up for text message alerts from your local government, and make sure your mobile devices are set to receive emergency alerts.
• Make an emergency plan that includes plans for family communication and evacuation. Practice your plan and keep it up to date.
• Map out routes to safe places on high ground or inland (away from the water). Your community may already have identified evacuation routes and assembly areas. Plan to evacuate on foot if you can; roads may be impassable due to damage, closures, or traffic jams. If you don’t think you would be able to reach a safe place in time, ask your local emergency management office about vertical evacuation. Some strong buildings, such as those made of reinforced concrete, may be able to provide protection if no other options are available.
• Practice walking your routes, even in darkness and bad weather. This will make evacuation quicker and easier during an emergency.
• Put together a portable disaster supply kit with items you and your family (including pets) may need in an emergency. Since you do not know where you’ll be when disaster strikes, prepare kits for work and cars, too. Consider storing supplies with family or friends outside of the tsunami hazard zone. Washington State Emergency Management recommends that each person prepare to be 2-Weeks Ready. Some coastal areas have additional recommendation for 30-day preparedness.
• Be a role model. Share your knowledge and plans with friends and neighbors so they can prepare themselves and their loved ones.
• If you have children in school in a tsunami hazard zone, find out the school’s plans for evacuating children and keeping them safe. Find out where the assembly area is and where to pick up your children after the danger has passed.
• If you’re visiting the coast, find out about local tsunami safety. Your hotel or campground should have this information.

Preparedness isn’t just for those on land. Those on the water either recreationally or as part of Washington’s maritime industry are also at risk from tsunamis. Tsunami risk is actually higher for mariners than for those on land, as even small tsunamis can cause significant hazards. Strong, rapidly shifting currents, scour and deposition of sediment, and movement of submerged and floating debris, can all have significant impacts, including operational disruptions and creation of navigational hazards. If you are a boat owner or captain you should take some extra steps to prepare for a tsunami:

• Make sure you have a way to receive tsunami warnings when you’re on the water. The U.S. Coast Guard will issue urgent marine information broadcasts on your marine VHF radio’s channel 16. Additional information will be available from NOAA Weather Radio.
• Find out what to do in your area if you get a tsunami warning when you’re on a boat. Your harbormaster, port captain, the U.S. Coast Guard, and local, state, and territory emergency management offices are the best sources for tsunami safety information and regulations for boaters in your area.
• Make a plan and put together a disaster supplies kit to keep onboard. Be aware that shore facilities may be damaged, so if you’re at sea during a tsunami, you may not be able to return to harbor. Be prepared to remain at sea for a day or more. In general, the following recommendations apply if you get a tsunami warning:
  • If you’re in a harbor, you should leave your boat and move quickly to a safe place on land (high ground or inland, away from the water).
  • If you’re at sea, you should move to a safe depth (safe depths vary by region, but the minimum safe depth is 30 fathoms—180 feet) and stay away from harbors under warning until officials tell you the danger has passed.

More detailed local information about preparedness, mitigation, and response plans are available for select ports and harbors with a Tsunami Maritime Resilience Strategy (TMRS). Read more about the TMRS reports in the Tsunami Maritime Hazards section of this webpage.

Vertical Evacuation Structures

We work with the WA Emergency Management Division (EMD) and local communities to facilitate the planning and design of tsunami evacuation structures. The first vertical tsunami evacuation structure in North America was built as part of a new elementary school in the Ocosta School District at Westport. The evacuation structure is designed to hold 1,000 people above the gymnasium. The surrounding area has little high ground for other types of evacuation.

Numerous other communities along the Washington coast are in the planning or proposal process to build vertical evacuation structures. For more information about building an evacuation structure in your community see the Manual for Tsunami Vertical Evacuation Structures developed by WA EMD.

Tsunami Evacuation Maps

Tsunami evacuation brochures and tsunami walk time evacuation maps are a few of the  products that we create to help people plan and prepare for evacuation from potentially inundated areas. Both types of maps feature our tsunami inundation mapping to define the area that must be evacuated. Tsunami evacuation routes were developed in coordination with local emergency management to assist coastal residents and visitors in finding safer locations in case of an earthquake and tsunami. Points of interest such as vertical evacuation structures (VES), assembly areas, and emergency services may also be identified on these maps to assist with wayfinding.

Walk time maps go a step farther in that they indicate the time it takes to evacuate from those inundated areas. This may be useful for understanding where evacuation may not be possible due to the long distance to reach high ground or barriers to reach it. For these areas, creating artificial vertical evacuation options or hardening evacuation pathways may be necessary.

Evacuation Maps

This map shows all completed tsunami evacuation brochures and walk time maps for Washington. Clicking on a region will show you a link where you can download the brochure or map. Use your scroll wheel or the plus and minus buttons in the upper left corner to zoom.

Sign up for our WA geology blog to get updates on when new tsunami evacuation maps are released.

Click on the areas of the map below to view and download walk time maps (in green) and evacuation brochures (in purple).

Click here to open the map in full screen.

Evacuation Brochures

Tsunami evacuation brochures are single sheets providing general information about tsunami evacuation. They show tsunami inundation extent, evacuation routes, and points of interest. They also contain basic information about tsunami evacuation and preparedness, and local emergency management contacts. Many of our previously released evacuation brochures have been replaced with walk time maps, which are a more data-rich product. Some regions may retain or have newly updated brochures, particularly where evacuation routing is clear and time to evacuate is short.

Walk Time Maps

Tsunami evacuation walk time maps show a more detailed view of the time it would take to evacuate on foot from the tsunami inundation zone. The maps also show how long it would take for the first tsunami wave to arrive. Emergency managers, planners, and local decision makers use these maps to plan evacuation routes, put in place critical resources, and plan response. The public should use these maps before the tsunami occurs, by learning the routes ahead of time for home, work, and school. These maps range in size from 11 x 17 inches to large 36+ inch map sheets.

How are Walk Time Maps Created?

The evacuation walk time maps are created from models that use the Pedestrian Evacuation Analyst Toolkit (PEAT). This toolkit was developed by the U.S. Geological Survey to aid in evacuation planning for natural hazards. The tool uses elevation changes and type of land cover to calculate walking speed along the evacuation route. Areas with steeper terrain or heavy vegetation will take longer to cross. The colors on the map show readers how long it takes to walk to high ground. The Washington Geological Survey works closely with each community’s emergency management and government representatives to determine the evacuation routes, shelters, and points of reference shown on each map.

What Walk Time Maps Can’t Tell Us

Walk time maps cannot predict the impacts of earthquakes, such as damage to buildings or infrastructure. During an earthquake, power lines may topple, underground utilities may rupture, and the ground may settle or shift. These unpredictable effects may slow evacuation time.

The maps also assume a slow walking pace of 2.5 mph. Not everyone travels at this pace, especially during an emergency. Determine how the times shown on the map compare to your own walking pace. This will give you a better estimate of how long it will take you to get to high ground.

Want to know if your house or neighborhood is at risk? Check out our Geologic Information Portal and type in your address to see if a tsunami evacuation map is available in your area. If there is no map available for your area, you can still see the tsunami hazard area overlaying the street view map, providing an opportunity to plan your own route. We encourage people to take the officially designated routes (denoted as dark red lines on our map products) where possible. However should there be no officially designated routes for your area, or if the official route has a hazard or blockage following an earthquake, feel free to take alternative pathways to safety.

Click the map icon to see tsunami content on the Geologic Information Portal.

The Northwest Association of Networked Ocean Observing Systems (NANOOS) has developed an interactive map of tsunami evacuation zones, routes, and assembly areas for both Oregon and Washington. This app is great for mobile devices and allows for geolocation while on the coast (provided cell services are available) and provides a simple hazard map with evacuation layers. In some parts of the Oregon and Washington coasts it also provides directions to the nearest high ground from a dropped marker.

 

Tsunami Hazard Maps

Looking for our new publication about the Alaska-Aleutian Subduction Zone earthquake and tsunami? Click here to download it.

A core component of our work is mapping where tsunami inundation is expected. This mapping is done for tsunamis generated by sources local to Washington such as the Cascadia subduction zone or Seattle Fault and from across the Pacific such as the Alaska-Aleutian Subduction Zone. We accomplish this by using specialized high-performance computing software to calculate tsunami wave heights and speeds as they progress across the ocean and onto land. These inundation models are based on the shape of the ocean floor, the topography of the land, and the expected size and shape of tsunami waves. These properties are derived from what we know about past earthquakes and tsunamis that are found in the geological record of the Pacific Northwest. The result of the modeling is brought into Geographic Information System (GIS) software and turned into maps, videos, and other products.

Our modeling publications generally show two properties of tsunami inundation: (1) the extent of inundation inland, and (2) current speeds in coastal and offshore waters.  Inundation and current speed map sheets and publications can be downloaded by clicking on your area of interest in the interactive maps below. You can also download the model data by clicking on your area of interest. You can use your scroll wheel or the plus and minus buttons in the upper left corner of each interactive map to zoom in and out. Sign up for our WA Geology Blog to get updates on when new tsunami hazard maps are released.

Tsunami hazards from an Alaska-Aleutian magnitude 9.2 earthquake scenario:

Click here to open the map in full screen.

Tsunami hazards from a Cascadia magnitude 9.0 earthquake scenario:

Click here to open the map in full screen.

Tsunami hazards from a Seattle Fault magnitude 7.5 earthquake scenario:

Click here to open the map in full screen.

Our modeling for a Tacoma fault earthquake scenario dates back to 2009 and may no longer be considered accurate given coastal development has led to significant land modifications, such as reconstruction of the waterway alignments at the Port of Tacoma. There are also significant improvements to the digital elevation models using elevation collected with lidar. These changes can affect modeling by significantly altering how much and where tsunami inundation occurs. For this reason, we no longer consider this modeling appropriate for use in evacuation or planning purposes, but may remain useful for general context of the relative severity of a Tacoma fault sourced event. Click here to download our Tacoma fault tsunami inundation publication. Note that this publication also contains modeling for a Seattle Fault earthquake scenario. Those results have been superseded by Map Series 2022-03, available by clicking on the map above.

Geologic Information Portal

All Washington coastlines and major lakes are at risk from tsunamis. Want to know if your house or neighborhood is at risk? Check out our Geologic Information Portal. Type your address into the search bar at the upper right corner of the screen to see if tsunami inundation has been mapped in your area.

Click the map icon to see tsunami content on the Geologic Information Portal.

Tsunami Maritime Hazards

Tsunamis are particularly hazardous for ports, harbors, and ships operating in waterways. Since ports and harbors must be located within and near coastal waters, they are at risk from tsunamis of all sizes. Even small tsunami waves of less than 3 feet can cause damage to docks and other infrastructure. Strong and unpredictable tsunami currents may impact port and harbor areas for hours. Improperly tied off ships or ships with inexperienced crews can damage ships and docks via collisions. Taking steps to mitigate the hazard today will reduce the damage from the next tsunami and speed up recovery times. We are partnering with Washington EMD to produce Tsunami Maritime Resilience Strategies (TMRS) for ports and harbors in Washington. The term Strategy indicates that these reports include information about how to mitigate for and respond to tsunami events rather than providing only hazard and evacuation information as WGS’s tsunami products typically do.  

These strategies cover much smaller areas than our broader inundation maps and can therefore be modeled in much greater detail. This detail is needed to understand the complex movement of water in areas filled with breakwaters, jetties, and unusually shaped boat basins. This detail includes modeling for a range of tidal stages and from multiple earthquake sources, giving us a much deeper understanding of the many possible impacts from potential tsunamis.  Maps of tsunami speeds can help us anticipate what damage to expect to port infrastructure in a future event. This information can also help guide mariners and port personnel in understanding what actions to take if they happen to be on the water when a tsunami alert is received.

Unique to these reports are water drawdown maps, which show how low the water gets during the drawdown phase of the tsunami. This identifies places where ships may be stranded on the floor of the harbor by the receding wave, and unable to maneuver before the next tsunami wave arrives.

Tsunami Maritime Response and Mitigation Strategies:

Click here to open the map in full screen.

Tsunami Simulation Videos

 

Tsunamis are multi-wave events that affect coastal areas for many hours to potentially days after an earthquake happens. To show how tsunamis might affect a certain area over time we use computer models to simulate how tsunami waves might behave for a given earthquake scenario. Videos of tsunami simulations show tsunami wave behavior in a way that is difficult to convey through static images and maps.

For more detailed tsunami wave heights for your area and for more information about tsunami inundation modeling, refer to our tsunami hazard maps.

Note that these videos are for informational purposes only and should not be used for site-specific decision-making.

Use the links below to view or download the videos for your area of interest. The videos are available on YouTube, or as downloadable zipped MP4 files.

Modeling for an Alaska-Aleutian Subduction Zone earthquake scenario

Simulation area map	Download simulation videos
	Washington Coast Tsunami Wave Amplitude: View video on YouTube  |  Download video in MP4 format

Modeling for a Seattle Fault earthquake scenario

Simulation area map	Download simulation videos
	Southern Bainbridge Island and Portions of the Kitsap Peninsula Tsunami Wave Amplitude: View video on YouTube  |  Download video in MP4 format Tsunami Current Velocity: View video on YouTube  |  Download video in MP4 format
	Seattle–Bainbridge Island Waterfronts Tsunami Wave Amplitude: View video on YouTube  |  Download video in MP4 format Tsunami Current Velocity: View video on YouTube  |  Download video in MP4 format
	Central Puget Sound Tsunami Wave Amplitude: View video on YouTube  |  Download video in MP4 format Tsunami Current Velocity: View video on YouTube  |  Download video in MP4 format

Modeling for a Cascadia magnitude 9 earthquake scenario

Simulation area map	Download simulation videos
	Washington Coast Tsunami Wave Amplitude: View video on YouTube  |  Download video in MP4 format
	Grays Harbor Tsunami Wave Amplitude: View video on YouTube  |  Download video in MP4 format Tsunami Current Velocity: View video on YouTube  |  Download video in MP4 format
	Pacific Beach Tsunami Wave Amplitude: View video on YouTube  |  Download video in MP4 format Tsunami Current Velocity: View video on YouTube  |  Download video in MP4 format
	Taholah Tsunami Wave Amplitude: View video on YouTube  |  Download video in MP4 format Tsunami Current Velocity: View video on YouTube  |  Download video in MP4 format
	Queets Tsunami Wave Amplitude: View video on YouTube  |  Download video in MP4 format Tsunami Current Velocity: View video on YouTube  |  Download video in MP4 format
	Willapa Bay Tsunami Wave Amplitude: View video on YouTube  |  Download video in MP4 format Tsunami Current Velocity: View video on YouTube  |  Download video in MP4 format
	Northern Willapa Bay Tsunami Wave Amplitude: View video on YouTube  |  Download video in MP4 format
	Southern Willapa Bay Tsunami Wave Amplitude: View video on YouTube  |  Download video in MP4 format
	Bellingham Tsunami Wave Amplitude: View video on YouTube  |  Download video in MP4 format Tsunami Current Velocity: View video on YouTube  |  Download video in MP4 format
	San Juan Islands Tsunami Wave Amplitude: View video on YouTube  |  Download video in MP4 format Tsunami Current Velocity: View video on YouTube  |  Download video in MP4 format
	Northern San Juan Islands Tsunami Wave Amplitude: View video on YouTube  |  Download video in MP4 format Tsunami Current Velocity: View video on YouTube  |  Download video in MP4 format
	Southern San Juan Islands Tsunami Wave Amplitude: View video on YouTube  |  Download video in MP4 format Tsunami Current Velocity: View video on YouTube  |  Download video in MP4 format
	Northern Hood Canal Tsunami Wave Amplitude: View video on YouTube  |  Download video in MP4 format Tsunami Current Velocity: View video on YouTube  |  Download video in MP4 format
	Southern Hood Canal Tsunami Wave Amplitude: View video on YouTube  |  Download video in MP4 format Tsunami Current Velocity: View video on YouTube  |  Download video in MP4 format

Tsunami Alerts

How will you know if a tsunami could be approaching? For people in Washington, the single biggest warning of a potential tsunami is a large earthquake. Once a tsunami has been created, there is usually a delay of several minutes to hours before it reaches land, depending on distance from the earthquake source. Scientists also use networks of ocean sensors to detect and monitor tsunamis.

The U.S. Tsunami Warning System is a system led by NOAA that operates in partnership with other local, state, federal, territorial, and international organizations as well as private industry. The system uses observation networks to detect and measure earthquakes that could generate tsunamis. The networks also allow us to monitor the tsunamis once they have been generated.

Washington State is served by the National Tsunami Warning Center (NTWC). Staffed 24 hours a day, seven days a week, this center monitors the observation networks, analyzes events as they occur, and, if necessary, provides advanced warning in case of a tsunami threat to the Washington coast. Information provided by the following networks helps the NTWC determine when and where to issue tsunami messages:

• Seismic networks—When an earthquake occurs, networks of seismic stations such as the Global Seismographic Network (GSN) and the Pacific Northwest Seismic Network (PNSN) provide information about an earthquake’s location, depth, magnitude, and other characteristics. The warning centers analyze this information to determine if tsunami messages are necessary.
• Water-level networks—If an earthquake meets certain criteria, the warning centers use information about water-level changes to determine if a tsunami has been generated and, if so, its size. The primary sources of information about water-level change are a network of deep ocean sensors (known as DART) and coastal water level stations.
• Coastal water-level stations collect important information about ocean height at specific coastal locations. The warning centers use this information to confirm tsunami arrival time and height and incorporate these findings into tsunami forecast models.

Warning people about tsunamis

In the U.S., tsunami warnings occur through the Emergency Alert System. In some beach communities, there are loud sirens that warn of a potential tsunami. You can subscribe to SMS, email, or phone notifications. Radio, television, and internet warning systems also exist. Contact your local emergency manager to ask about tsunami alert information for your area.

Although substantial loss of life can occur with any major tsunami, people who are warned ahead of time are better prepared to survive. Different types of alerts let people know what actions need to be taken once they receive the alert.

Tsunami Warning

A tsunami warning is issued when a tsunami with the potential to generate widespread inundation is expected. Warnings alert the public that dangerous coastal flooding accompanied by powerful currents is possible and may continue for several hours after initial arrival. This is the most urgent type of alert. Upon receiving this alert you should follow instructions from local officials if provided, and immediately evacuate to high ground or inland (away from the water) if you are in a coastal area.

Tsunami Advisory

A tsunami advisory indicates when a tsunami is expected, but differs from a warning in that the tsunamis waves are not expected to cause severe coastal flooding. People are advised to stay out of the water, off beaches, and out of low-elevation areas that may be subject to flooding. The threat of a tsunami may continue for several hours after initial arrival.

Tsunami Watch

A tsunami watch is issued when a tsunami may later impact the watch area. The watch may be upgraded to a warning or advisory or canceled based on updated information and analysis. Emergency management officials and the public should prepare to take action.

Information Statement

A tsunami information statement is issued when an earthquake or tsunami has occurred that may be of interest to coastal residents. In most cases, information statements indicate there is no threat of a destructive basin-wide tsunami and that evacuation is unnecessary at the present time.

Historical Tsunamis Worldwide

The list below shows a selection of major tsunamis that have happened in recorded history. This does not represent an exhaustive list of tsunamis found worldwide (see NOAA NCEI Global Historical Tsunami Database). These are events that have happened in recent history and gained media attention or have been fundamental to the understanding of tsunami hazards locally and globally.

Some Historical Tsunamis
Name	Date	Original Location	Max Wave Height	Source of Tsunami	Earthquake Magnitude
Tracy Arm Notes: A 130 million cubic yard landslide occurred in the Tracy Arm fjord in Alaska. This landslide produced a tsunami with a maximum runup of 1,580 feet making it the second highest recorded in history (following Lituya Bay). Fortunately there were no injuries or fatalities from this event as the landslide and tsunami occurred early in the day before cruise ships arrived (typically 3 per day visit this site in summer months).	Aug. 10, 2025	Alaska	1,580 feet	Landslide	N/A
Kamchatka Notes: A subduction zone earthquake from the Kuril-Kamchatka subduction zone produced the largest earthquake since the Tohoku earthquake and tsunami of 2011. Despite the size of the earthquake, the resulting tsunami was smaller than anticipated, with 33-49 ft wave heights recorded over much of the Russian coast and rare waves reaching up to 109 ft in select locations. Similarly, the tsunami had a less-extensive humanitarian impact, with only one fatality and 25 injuries recorded worldwide.	July 29, 2025	Russia	65 feet	Earthquake	M8.8
Tonga Notes: The eruption of Hunga Tonga-Hunga Haʻapai volcano triggered a tsunami that killed 4 people and displaced 1,500. Despite being a volcanically triggered event, the Tsunami Warning Centers were able to detect and issue an alert for the tsunami. Another notable aspect of the eruption is that the blast created an air pressure wave that formed a meteotsunami. This meteotsunami traveled so far that it was detected in other ocean basins, such as the Caribbean.	Jan. 15, 2022	Tonga	65 feet	Volcanic Eruption	N/A
Sunda Strait Notes: The eruption and collapse of the volcano Anak Krakatau triggered a tsunami that killed nearly 430 people. The tsunami was not detected and people were not alerted due to a lack of adequate warning systems. The tsunami also occurred at night, restricting visual warning signs.	Dec. 22, 2018	Indonesia	43 feet	Volcanic Landslide	N/A
Sulawesi Notes: A shallow earthquake caused a tsunami that hit coasts locally in the Sulawesi area. The earthquake caused major soil liquefaction, leading to mudflows. The combined tsunami and earthquake caused more than 4,300 deaths.	Sept. 28, 2018	Indonesia	23 feet	Earthquake	M7.5
Tohoku Notes: Nearly 20,000 people were killed and a major nuclear power plant meltdown occurred. A Cascadia subduction zone earthquake off the coast of Washington could be similar to the Tohoku event, producing significant waves impacting coastlines in the Pacific Northwest.	Mar. 11, 2011	Japan	130 feet	Subduction Zone Earthquake	M9.0
Indian Ocean Notes: One of the most devastating natural disasters in history with nearly 280,000 deaths and more than 1 million people displaced. The lack of a tsunami warning system in the Indian Ocean meant that people did not know to evacuate after the earthquake.	Dec. 26, 2004	Sumatra, Indian Ocean	108 feet	Subduction Zone Earthquake	M9.2
Spirit Lake Notes: A large landslide from the Mount St. Helens eruption caused an enormous tsunami in Spirit Lake.	May 18, 1980	Spirit Lake, Washington	853 feet	Volcanic Landslide	N/A
Good Friday Earthquake Notes: Third-strongest earthquake in recorded history—shaking lasted for 3 minutes. Tsunami caused damage throughout the Pacific Ocean, including 110 deaths, some as far away as Crescent City, California. Also caused a large underwater landslide that created a 200-foot tsunami in Valdez Inlet.	Mar. 27, 1964	Alaska	100 feet	Subduction Zone Earthquake	M9.2
Lituya Bay Notes: An earthquake on the Fairweather fault caused 39 million cubic yards of rock and ice (a cube of land ~1,000 feet on each side) to fall into the ocean. The resulting 'splash' destroyed everything on shore up to 1,720 feet above sea level and sent a huge tsunami into the bay. This is the largest tsunami in history.	July 9, 1958	Lituya Bay, Alaska	1,720 feet	Earthquake-Triggered Landslide	M7.8
Aleutian Islands Tsunami Notes: The tsunami from this earthquake caused 165 deaths and significant destruction in Alaska, Hawaii, and other states and countries bordering the Pacific Ocean. It resulted in the formation of the Pacific Tsunami Warning Center.	Apr. 1, 1946	Alaska	130 feet	Subduction Zone Earthquake	M8.1
Krakatoa Notes: The explosion from this volcanic eruption is thought to have been the loudest sound in modern history, reaching people over 3,000 miles away. The collapse of the magma chamber beneath the ocean floor caused a tsunami throughout the southern Pacific Ocean and killed at least 36,000 people. The ash from the eruption changed global weather patterns for several years.	Aug. 26–27, 1883	Sunda Strait, Indonesia	125 feet	Volcanic Eruption and Collapse	N/A
All Saints Day Notes: This earthquake and tsunami occurred during mass on All Saints Day and killed at least 40–50,000 people in Lisbon alone. The ocean receded as the tsunami approached, and many people ran to the beach to escape the earthquake’s destruction, only to be faced with a tsunami. This event appears to be the first scientifically studied earthquake and is credited as founding the modern field of seismology.	Nov. 1, 1755	Offshore of Lisbon, Portugal	50 feet	Earthquake of Unknown Type	M8.5–9.0
Cascadia Notes: The tsunami created during this event is recorded in the geologic record and in Native American oral history. The tsunami may be the inspiration for the battle of the Thunderbird and Whale. Japanese records precisely document the tsunami from this event because it also caused significant destruction along the coast of Japan.	Jan. 26, 1700	Washington—Oregon coast	~100 feet	Subduction Zone	M8.7–9.2

Building Code Design Zone Map

Click here to go to a webpage that provides information on Tsunami Design Zone Maps (WA-TDZ). Washington State building code requires that designers, engineers, and architects use the WA-TDZ to determine whether certain structures need to be designed for tsunamis.