Californians pride themselves on keeping their cool when the earth shakes, but for residents living along the coastline, it’s when the shaking stops that a new potential threat begins.
More than 150 tsunamis have hit California’s shore since 1800. Most were barely noticeable, but a few have caused fatalities or significant damage. The most destructive tsunami to hit California occurred on March 28,1964. Several surges reaching 21 feet high swept into Crescent City four hours after a magnitude 9.2 earthquake in Alaska, killing 12 people and leveling much of the town’s business district.
More recently, a tsunami threat for the West Coast was canceled in the middle of the night on July 29, 2021, after a magnitude 8.2 earthquake struck off the Alaska Peninsula, approximately 65 miles southeast of Perryville. In the earthquake’s immediate aftermath, images from surrounding communities showed residents evacuating and seeking higher ground, prompted by local authorities. There were no initial reports of injuries or damages.
With over 1,200 miles of coastline, all Californians should familiarize themselves with the warning signs of an impending tsunami and know how to move quickly to safety zones in higher ground.
Tsunamis can hit coastal areas within minutes after a severe earthquake. The best way to protect yourself and your family in case of a tsunami is to follow instructions and evacuate when told to do so, in case of a long/strong earthquake:
- Move to higher ground.
- Stay away from coast, tidal estuaries, rivers and streams; if at sea, stay there until “all clear” is issued.
- Be aware of secondary hazards such as landslides, flooding and mudflows.
Prepare BEFORE
- Find out if your home, school, workplace or other frequently visited locations are in tsunami hazard areas. For high risk areas, know the earthquake and tsunami plans for each location.
- Contact your municipality to know the risks, evacuation and alerting system in your community. Know the sound of the alert and make sure your family members are familiar with it and what to do. Sign up for local alerts.
- Know the difference between a tsunami warning and a tsunami watch:
A tsunami warning means a tsunami may have been generated and could be close to your area. A full evacuation is suggested.
A tsunami watch means a tsunami has not yet been verified but could exist and may be as little as an hour away. Stay alert for more information.
- Review evacuation plans with household members. Be prepared to evacuate at a moment’s notice.
- Plan evacuation routes to areas 30 meters above sea level or 3 kilometers inland. If you can’t, go as high and as far away as you can. You should be able to reach your safe location on foot within 15 minutes.
Survive DURING
- If you feel an earthquake, drop, cover and hold on:
Drop to your hands and knees to avoid being knocked down. Crawl under heavy furniture such as a table, desk, bed or any solid furniture.
Cover your head and torso to prevent being hit by falling objects.
Hold onto the object you are under so that you remain covered.
- Be aware of the signs of a tsunami:
A strong earthquake lasting 20 seconds or more near the coast.
A noticeable rapid rise or fall of coastal waters.
Coastal water making unusual noise. The noise may sound like an approaching train, plane, or whistling.
- Following an earthquake, move quickly to higher ground away from the coast. In case of a tsunami warning, be ready to evacuate at a moment’s notice.
- Follow posted evacuation routes, where present. Take your animals with you.
- A tsunami is a series of waves that can continue for hours and the next waves may be larger than earlier ones. Do not assume that after one wave, the danger is over. If you cannot evacuate to higher ground, evacuate vertically to a higher floor, onto a roof, up a tree, or grab a floating object.
- If you are at sea, stay there. Boats are generally safer in water deeper than 20 meters. Ships are safest on high seas in water deeper than 100 meters.
- Watching a tsunami could put you in grave danger. If you can see the wave, you are too close to escape it.
- Monitor the tsunami’s progress and listen for warnings or instructions from local officials. If you are safe when the first tsunami hits, stay put until authorities declare all is safe as more waves may follow.
Be Safe AFTER
- Continue to take precautions and listen to and follow directions from local authorities.
- Be prepared for earthquake aftershocks, which could generate another tsunami.
- Return home only after local officials tell you it’s safe.
- Be aware of secondary effects. These include landslides, contaminated water, mudflows, damaged bridges, buildings and roads, and other hazards.
- Only make calls if you require emergency services.
- Stay out of any building that has water around it. Tsunami force can cause floors to crack or walls to collapse.
- If you suspect your home is unsafe, do not enter. Rely on the professionals to clear your home for re-entry, if you are unsure.
- Do not light matches or turn on lights or appliances until you are sure there are no gas leaks or flammable liquids spilled. Avoid use of contaminated water.
- Place a HELP sign in your window if you need assistance.
RESOURCES
CalOES MyHazards Tool
Learn more about the risk for tsunamis and other natural hazards (including earthquakes, floods, and fire) in your neighborhood, and how to reduce your risk at MyHazards, a tool provided by the California Governor’s Office of Emergency Services.
Tsunami Inundation Maps
California tsunami inundation maps show where areas on land can become quickly flooded from a tsunami’s waves. These maps can be used by anyone to plan a safe evacuation route.
Preparedness
A collection of tsunami preparedness materials specific to California is listed below.