What is tsunami inundation

Run-up is the more damaging force than the huge tsunami waves as it surges inland and destroys all in it's path. The first wave in a tsunami train doesn't always produce the highest run-up. Scientists have tried to explain why and found that a tsunami's frequency that is how closely in time one wave follows another combined with a shoreline's slope can result in a resonance that sends more water onshore. A receding tsunami wave looks like a pendulum about to fall.

It holds tremendous energy. If this receding wave collides with an incoming tsunami wave releasing this kinetic energy, it forces the incoming wave to mount and increase in size. The same resonance happens when an adult pushes a child on a swing.

If the adult gives the child a push right when the child is at her highest point, she will swing higher in the next arc. Another push at just the right moment will send her even higher. In the same way, when the two tsunami waves meet at just the right moment, it causes the inbound wave to go higher on the shore. The topography of the shoreline dictates the potential height of the wave. Tsunamis generated far away from the coast of Hawaii are considered distant tsunamis.

The following are the estimated times that waves will reach Hawaii for tsunamis generated in various locations around the world.

The most important thing during a Tsunami Warning is to get out of the evacuation zone as soon as possible. Anywhere outside the evacuation zone is a safe place. If possible, make plans to evacuate to a family member or friend's home who lives outside the evacuation zone.

During a Tsunami Warning, car traffic may be heavy and can cause delays, so plan to walk to a safe location if possible. If you are near high-rise buildings when an evacuation order is issued, consider vertical evacuation.

To vertically evacuate, proceed to the fourth floor or higher of a building that is 10 stories or taller. If time permits, public facilities with restrooms and parking may be made available. These will be announced on local media, such as TV, radio, and official social media channels. These are not shelters and will not have other services. Shelters will only open, if needed, following a tsunami wave arrival.

If you are not located in a tsunami evacuation zone and a Tsunami Warning is issued, stay home and stay off the road. We want to keep roads and highways open for evacuees leaving the coastline and provide emergency access to first responders who will be assisting with the evacuation. On Oahu, a number of Hawaii Public Schools are located within existing tsunami evacuation zones. These schools hold evacuation drills so that they are able to safely and quickly evacuate their students and staff.

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. How will you know if a tsunami could be approaching? 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. Example of a Tsunami travel time map from the Alaska Earthquake.

In this event the first wave reached Washington in approximately four hours. Image by NCEI. The U. 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.

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 these networks helps them determine when and where to issue tsunami messages.

In the U. 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. A tsunami warning is issued when a tsunami with the potential to generate widespread inundation is expected or currently approaching.

Warnings alert the public that dangerous coastal flooding accompanied by powerful currents is possible and may continue for several hours after initial arrival. A tsunami advisory indicates if a tsunami is expected or currently approaching, but differs from a warning in that the tsunamis waves are not expected to be as high. People are advised to stay away from the coast. The threat of a tsunami may still continue for several hours after initial arrival.

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. 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.

The list below shows a selection of major tsunamis with notable scientific or cultural impact that have happened in recorded history. Skip to main content. Public Land Survey Office. Assessing Species Vulnerability. Partners Meeting. Rural Broadband. Virtual Legislative Tours. Jobs Start a Career Internships. Search form Search. Read this page. Understanding tsunamis Tsunamis in Washington Preparation and evacuation Tsunami evacuation maps Tsunami hazard maps Tsunami simulation videos Tsunami alerts Historical tsunamis worldwide Building code design zone map Understanding tsunamis In order to prepare for tsunamis we must first understand them.

What is a tsunami Local and distant tsunamis What causes tsunamis A tsunami is a powerful and destructive natural force. 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 or Tacoma faults 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 Depends on where the landslide occurs Minutes to tens of minutes Below is a map of notable locally derived tsunamis that have occurred in Washington during historic times.

Earthquake sources Evidence of past earthquakes and tsunamis 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 biggest tsunami hazard for Washington State.

Crustal Faults Other faults in Washington, such as the Seattle Fault, can also move the ocean floor and cause tsunamis. Distant Events Tsunamis generated from earthquakes at other subduction zones and faults around the Pacific Ocean have the potential to impact our shores. Preparation and evacuation It is important to know the warning signs of a tsunami. Know what to expect. Know what to do. 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.

Your harbormaster, port captain, the U. 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 prepared to remain at sea for a day or more.

If your home, school, workplace, or other places you visit often are in tsunami hazard zones, you should do the following: 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.

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. Consider storing supplies with family or friends outside of the tsunami hazard zone. Some coastal areas have additional recommendation for day preparedness. Be a role model. Share your knowledge and plans with friends and neighbors so they can prepare themselves and their loved ones. Find out where the assembly area is and where to pick up your children after the danger has passed.

Your hotel or campground should have this information. Tsunami evacuation maps Tsunami evacuation routes were developed to assist coastal residents and visitors in finding safer locations in case of an earthquake and tsunami.

Evacuation Maps This map shows all completed tsunami evacuation brochures orange and walk time maps blue for Washington. Evacuation Brochures Tsunami evacuation brochures are single sheets providing general information about tsunami evacuation.

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

Tsunami hazard maps The mission of the Washington Geological Survey WGS is to collect, develop, use, distribute, and preserve geologic information to promote the safety, health, and welfare of the citizens, protect the environment, and support the economy of Washington.

Geologic Information Portal All Washington coastlines and major lakes are at risk from tsunamis. Tsunami simulation videos. Tsunami alerts How will you know if a tsunami could be approaching? 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. Tsunami Warning A tsunami warning is issued when a tsunami with the potential to generate widespread inundation is expected or currently approaching. Tsunami Advisory A tsunami advisory indicates if a tsunami is expected or currently approaching, but differs from a warning in that the tsunamis waves are not expected to be as high. Tsunami Watch A tsunami watch is issued when a tsunami may later impact the watch area.

Information Statement A tsunami information statement is issued when an earthquake or tsunami has occurred that may be of interest to coastal residents.

Historical tsunamis worldwide The list below shows a selection of major tsunamis with notable scientific or cultural impact that have happened in recorded history. The earthquake caused major soil liquefaction, leading to mudflows. The combined tsunami and earthquake caused more than 4, deaths. Sunda Strait Dec. The tsunami was not detected by warning systems because it was not caused by an earthquake. Tohoku Mar. The Tohoku event is similar to what is expected for the Cascadia subduction zone off the coast of Washington.

Indian Ocean Dec. A lack of a tsunami warning system in the Indian Ocean meant that people did not know to evacuate after the earthquake. Helens eruption caused an enormous tsunami in Spirit Lake. Good Friday Earthquake Mar. Tsunami caused damage throughout the Pacific Ocean, including deaths, some as far away as Crescent City, California.

Also caused a large underwater landslide that created a foot tsunami in Valdez Inlet. Lituya Bay Jul. The resulting 'splash' destroyed everything on shore up to 1, feet above sea level and sent a huge tsunami into the bay.

This is the largest tsunami in history. Aleutian Islands Tsunami Apr.