Your Local Risks · Hazard Guide
A tsunami generated by a local earthquake can reach the coast in minutes. The earthquake itself is the warning. Knowing your evacuation zone and route to high ground before it happens is the entire preparedness strategy.
Understanding the hazard
A tsunami is not a single breaking wave. It is a series of surges, sometimes described as a rapidly rising tide that does not stop. The water can push inland for hundreds of yards or miles depending on coastal topography, carrying debris, vehicles, and structures with it. The first surge is not always the largest.
Tsunamis are generated by undersea earthquakes, volcanic eruptions, or submarine landslides. In the Pacific Northwest, the Cascadia Subduction Zone is capable of producing a magnitude 9.0 earthquake that could send a tsunami onshore in as little as 15 to 20 minutes. The 1964 Good Friday earthquake in Alaska generated a tsunami that killed people as far away as Crescent City, California.
The critical distinction is between local and distant tsunamis. A local tsunami from a nearby earthquake gives you minutes. A distant tsunami from across the Pacific gives you hours and triggers formal warnings through the Pacific Tsunami Warning Center. For local events, you are the warning system. If the ground shakes hard for 20 seconds or more near the coast, move to high ground immediately.
Know your exposure
Tsunami risk varies enormously by coastline. If you live, work, or vacation on the coast, know which zone you're in.
Washington, Oregon, and Northern California face the highest risk from the Cascadia Subduction Zone. A full rupture could produce a tsunami reaching coastal communities in 15 to 20 minutes. Some areas have vertical evacuation structures.
The most seismically active state in the U.S. Alaska generates more tsunamis than any other state and has the most extensive tsunami warning infrastructure. Coastal communities practice regular evacuation drills.
Exposed to both local and distant tsunamis from across the Pacific basin. Hawaii has a well-established siren warning system and detailed inundation zone maps. Hilo has been struck by destructive tsunamis multiple times.
Lower risk but not zero. Submarine landslides, the Canary Islands volcanic flank, and the Puerto Rico Trench all present potential sources. Caribbean communities have the highest exposure on this coastline.
Before it happens
Walk your route to high ground. Time it. The target is 100 feet above sea level or at least one mile inland on flat terrain. Know at least two routes in case one is blocked. If you live or work in a tsunami zone, this is the single most important thing you can do.
Some coastal communities have designated vertical evacuation structures: reinforced concrete buildings, parking garages, or purpose-built tsunami shelters. If you cannot reach high ground, the third floor or above of a reinforced concrete building may be your best option.
After a major earthquake, roads may be cracked, blocked, or jammed with traffic. Evacuation on foot is often faster and more reliable than driving. A go-bag with shoes, a flashlight, water, and essential medications should be staged near your door.
Wireless Emergency Alerts, NOAA Weather Radio, and local tsunami sirens (where installed). For distant tsunamis, formal warnings provide hours of lead time. For local tsunamis, the earthquake is the warning. Do not wait for sirens. Move.
The key skill
If you are near the coast and any of these happen, evacuate immediately to high ground. Do not wait for confirmation.
A long, strong earthquake near the coast is the most reliable natural warning. Drop, cover, and hold during the shaking. The moment shaking stops, grab your go-bag and move to high ground immediately. Do not return until officials give an all-clear.
If the ocean pulls back dramatically, exposing sea floor that is normally underwater, a tsunami surge is likely incoming. This is not the time to investigate. Run inland or uphill immediately.
Wireless Emergency Alerts or tsunami sirens mean evacuate now. Move to your predetermined high-ground location. Stay there until officials issue an all-clear. Tsunami surges can continue arriving for hours.
The first surge is not always the largest. Tsunami waves can arrive in series over several hours. Do not return to low-lying areas until emergency management confirms it is safe. Monitor NOAA Weather Radio or local emergency channels.
Official resources
Next step
Tsunami evacuation happens fast. A staged go-bag with shoes, water, flashlight, medications, and documents means you leave in seconds instead of minutes. The First 72 Hours guide covers what goes in and where to keep it.
First 72 Hours guide"Those who cannot remember the past are condemned to repeat it."
— George Santayana
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