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MARCH 21-25
tsunami prep week
is our coastal area at risk?



During California Tsunami Preparedness Week you can learn about: 

• causes

• impacts

• zones

• warnings

• planning and preparedness

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Tsunamis are a major threat to coastal communities, typically causing the most severe damage and casualties very near their source. Strong currents generated by a tsunami can injure and drown swimmers and damage and destroy boats and infrastructure in harbors. Low-lying areas such as beaches, bays, lagoons, harbors, river mouths, and areas along rivers and streams leading to the ocean are the most vulnerable.

/  causes & impacts  /

California's Tsunami Preparedness Week is March 21- 25. 

Cal OES, the California Geological Survey, and the National Weather Service coordinate through the California Tsunami Program to assist local coastal partners with planning activities.

Rare, but be aware!

Although catastrophic tsunamis are rare. We may have a tendency to get complacent and think that one will never happen while we’re at the beach. However, every coastline in the world is vulnerable to a tsunami. While a tsunami cannot be prevented, you can diminish adverse impacts through community preparedness, timely warnings and effective response.

A tsunami is one of the most powerful and destructive natural forces. It is a series of waves caused by a large and sudden displacement of the ocean. Tsunamis are a serious threat to life and property. Most tsunamis are caused by large earthquakes below or near the ocean floor, but can also be caused by landslides, volcanic activity, certain types of weather, and near-earth objects. In the deep ocean, tsunami waves are often barely noticeable, but can move as fast as a jet plane, over 500 mph. As they enter shallow water near land, they slow down and grow in height, and currents intensify.

While tsunamis can occur in any oceanic region in the world, more large earthquakes take place on the Pacific Ocean basin than anywhere else.

causes & impacts
tsunami zones

/  tsunami zones  /

Know your zone

California Tsunami Hazard Area Maps are produced collectively by the California Governor's Office of Emergency Services, the California Geological Survey, AECOM Technical Services, and the Tsunami Research Center at the University of Southern California.

This map shows the hazard zones and safe zones along the California coast. You are encouraged to use the interactive map found on the California Department of Conservation website: to locate your home and your workplace on the map, and determine an evacuation route in the event of a pending tsunami. 

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/  tsunami warnings  /


Warning signs

Tsunami hazard zones can be located with strategically placed signs in specific areas to delineate the perimeter of the inundation zone, evacuation routes and appropriate action to be taken by individuals when an earthquake occurs.

In California, the signs shown below were approved by the California Department of Transportation for use in tsunami inundation areas.

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There are four levels of tsunami alerts in the United States:

• Warning

• Advisory

• Watch

• Information Statement

When the centers issue Tsunami Warnings, they are broadcast through local radio and television, wireless emergency alertsNOAA Weather Radio and NOAA websites (like They may also come through outdoor sirens, local officials, text message alerts, and telephone notifications.

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plan & prepare


  • The first wave isn’t the biggest

  • Rapid recession of water is a warning sign

  • Can travel up to 600 mph

  • Can occur following an earthquake

Most tsunamis are not one big breaking wave that overruns the shore. They are usually a series of waves behaving similar to a rapidly rising high tide that can continue repeatedly over many hours, and even days.


In most cases, the first in the series of waves is not the biggest. A tsunami may start small, relatively speaking, and develop over time. People have been killed most often by subsequent waves, coming hours after the “start of tsunami.”


Tsunamis travel faster over the open ocean than they do toward land. In the open ocean the travel a speeds of up to 600 mph, about the speed of a jet


Not all tsunamis are recognizable by the fast recession of water from the shore. Only about 40% of tsunamis produce this natural warning sign.

/  plan & prepare  /


How to Prepare for a Tsunami

Education and preparation are the best ways to avoid injury and increase your chances for survival. Whether you live, work, or visit in California, it is important to be aware that the coastal region is vulnerable to tsunamis. Tsunamis can be generated locally or come across the ocean great distances.


California’s large active offshore faults and unstable submarine slopes can cause tsunami activity along the coast. Strong ground shaking from an earthquake is the natural warning that a tsunami might be coming. If you are on the beach or in a harbor and feel an earthquake, immediately move inland or go to high ground. If strong shaking lasts for 20 seconds or more, everyone within the tsunami evacuation area should evacuate as soon as it is safe to do so.

Other natural warnings include seeing the ocean quickly recede to expose the ocean bottom, or hearing an unusually loud roar coming from the ocean. A tsunami can arrive within minutes and may last for several hours. 


For tsunamis coming from across the ocean, local communities use a variety of communication methods to broadcast emergency information. Be informed on what signals, sirens, and public services will be employed for your area. Practice tsunami evacuation drills.

Know whether you are in a potential tsunami zone by observing street signs or looking online to see if you are in a zone. Know the evacuation routes for your area. Have a “Go bag” ready, in the event you have to evacuate. Do not return to the evacuated zone until officials tell you it is safe to do so. The first tsunami is not always the largest, and tsunami waves, flooding and strong currents can last for several hours.

Prepare NOW

  • Learn the signs of a potential tsunami, such as an earthquake, a loud roar from the ocean, or unusual ocean behavior, such as a sudden rise or wall of water or sudden draining of water showing the ocean floor.

  • Know and practice community evacuation plans. Map out your routes from home, work and play. Pick shelters 100 feet or more above sea level, or at least one mile inland.

  • Create a family emergency communication plan that has an out-of-state contact. Plan where to meet if you get separated.

  • Sign up for your community’s warning system; Alert SouthBay. The Emergency Alert System (EAS) and National Oceanic and Atmospheric Administration (NOAA) Weather Radio also provide emergency alerts.

  • Consider earthquake insurance and a flood insurance policy through the National Flood Insurance Program (NFIP). Standard homeowner’s insurance does not cover flood or earthquake damage.

Survive DURING

  • If there is an earthquake and you are in a tsunami area, protect yourself from the earthquake first. Drop, Cover, and Hold On. Drop to your hands and knees. Cover your head and neck with your arms. Hold on to any sturdy furniture until the shaking stops. Crawl only if you can reach a better cover, but do not go through an area with more debris.

  • When the shaking stops, if there are natural signs or official warnings of a tsunami, move immediately to a safe place as high and as far inland as possible. Listen to the authorities, but do not wait for tsunami warnings and evacuation orders.

  • If you are outside of the tsunami hazard zone and receive a warning, stay where you are unless officials tell you otherwise.

  • Leave immediately if you are told to do so. Evacuation routes often are marked by a wave with an arrow in the direction of higher ground.

  • If you are in the water, then grab onto something that floats, such as a raft or tree trunk.

  • If you are in a boat, face the direction of the waves and head out to sea. If you are in a harbor, go inland.


  • Listen to local alerts and authorities for information on areas to avoid and shelter locations.

  • Save phone calls for emergencies. Phone systems often are down or busy after a disaster. Use text messages or social media to communicate with family and friends.

  • Avoid wading in floodwater, which can contain dangerous debris. Water may be deeper than it appears.

  • Be aware of the risk of electrocution. Underground or downed power lines can electrically charge water. Do not touch electrical equipment if it is wet or if you are standing in water.

  • Stay away from damaged buildings, roads and bridges.

  • If you become injured or sick and need medical attention, contact your healthcare provider and shelter in place, if possible. Call 9-1-1 if you are experiencing a medical emergency.

  • Document property damage with photographs. Conduct an inventory and contact your insurance company for assistance.

Maritime Preparedness

The California Office of Emergency Services and California Geological Survey have produced a tsunami preparedness brochure for recreational and commercial boaters. The March 11, 2011 tsunami caused nearly $100M in damage to the California maritime community. The California tsunami program is working with the state’s maritime communities to provide more detailed maps and guidance that will help them improve their tsunami planning. This brochure will help educate individual boaters about how they should prepare BEFORE the next tsunami arrives on our coast. Tsunami Preparedness Brochure for Recreational and Commercial Boaters


Tsunami Preparedness Information Links


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