Case Study · Tsunami · 1964
On March 27, 1964, the largest earthquake in North American history struck Alaska. Hours later, in Crescent City, California, three small waves came and went. People walked back into downtown to check on their property. Then the fourth wave arrived — 21 feet high — and destroyed 29 city blocks. The central tsunami lesson: the first wave is never the last.
Good Friday Earthquake & Tsunami · March 27, 1964
Good Friday, March 27, 1964. In Anchorage, Alaska, it was late afternoon and most people were home from work. The Easter holiday had kept schools and offices empty. At 5:36 PM local time, the ground began to shake — and kept shaking for four and a half minutes, one of the longest and most powerful earthquakes ever felt on Earth. The magnitude 9.2 event, centered in Prince William Sound, caused Anchorage to heave and buckle. The Government Hill Elementary School was destroyed by a landslide. Downtown Anchorage fractured along fault lines. The earthquake killed 15 people directly.
What followed was far worse. The earthquake displaced an enormous section of the ocean floor, generating a series of tsunami waves that radiated outward from Alaska across the Pacific. In coastal Alaskan communities — Valdez, Seward, Whittier, Chenega — locally generated tsunamis arrived within minutes of the shaking, with devastating effect. In Valdez, spectators who had come to watch a ship unload at the city dock were swept into the water. In Chenega, a wave that arrived nine minutes after the quake killed 23 of the village's 68 residents — a third of the community. Far to the south, the trans-ocean wave was still traveling.
March 27, 1964
Date
139
Total Deaths
$116M
1964 Dollars
Alaska → CA
Reach
9.2 Mw
Magnitude
By midnight, the trans-ocean tsunami had struck Crescent City, California — a small city of 3,000 that juts into the Pacific on California's far north coast. A warning had been issued. California's Civil Defense office had received it at 9:30 PM. County alerts weren't issued until 11:08 PM. The estimated time of arrival was midnight. Deputies had less than an hour to evacuate coastal areas. Three relatively small waves arrived and retreated. Some residents went back downtown. Then the fourth wave — nearly 21 feet high — swept through 29 city blocks and killed 11 to 13 people. Most of them had survived the first three waves. They went back because the waves seemed to be getting smaller. The tsunami had not finished.
The Science
Think of a tsunami not as a tall wave but as a column of water in motion — a pulse of energy moving through the entire depth of the ocean, not just the surface. When an earthquake displaces a section of ocean floor, it doesn't create a single wave. It creates a series of wave trains — multiple crests and troughs radiating outward. These waves travel at the speed of a jetliner in deep water (500–600 mph) and slow dramatically as they approach shore, where the ocean floor shallows. As they slow, their height increases. A wave that was barely detectable in deep ocean can become a wall of water 20 feet tall or more when it reaches a shallow coastal shelf or harbor.
A single earthquake produces a complex wave train — multiple waves with different periods (the time between crests). The waves interact with each other, with submarine topography, and with coastal geometry in ways that make the sequence unpredictable without specialized modeling. The 1964 event at Crescent City produced three relatively modest waves followed by a much larger fourth wave. This is not unusual for tsunamis — the largest wave in a series is often the second, third, or fourth, not the first. The Redwood Coast Tsunami Work Group's account of 1964 documents that many of the Crescent City deaths occurred because the apparent diminution of the early waves led people back into the hazard zone before the last and largest wave arrived.
The 1964 earthquake killed most of its Alaskan victims through locally generated tsunamis — waves created by underwater landslides within the fjords and bays near the earthquake epicenter. USGS research on the 1964 event established that approximately 85 of the 106 Alaska tsunami deaths came from these local waves, which arrived within minutes of the shaking — far faster than any warning system could communicate. In Valdez, the water first retreated from shore as an underwater slide drew it back, then returned as a massive surge. For communities near a major subduction zone, the earthquake itself is the only warning there is time to act on.
Timeline
01
Centuries of stress accumulation on the Aleutian subduction zone. The Pacific Plate has been diving beneath North America, locked at the interface and building stress. The Cascadia Subduction Zone (which runs from northern California to British Columbia) has the same structure. On March 27, 1964 at 5:36 PM AST, the locked fault releases — one of the largest seismic energy releases ever recorded.
02
March 27, 5:36 PM: Magnitude 9.2. Four and a half minutes of shaking. Anchorage infrastructure destroyed. Immediately, local tsunamis generated by underwater landslides in Prince William Sound strike Valdez, Seward, Whittier, and Chenega within minutes. No warning is possible for these communities. 82 of the 106 Alaska tsunami deaths occur in this window.
03
March 27–28, overnight: The trans-ocean tsunami travels south at jetliner speed. Warning alerts are issued but communications are slow. California's Civil Defense receives the alert at 9:30 PM but doesn't issue county warnings until 11:08 PM — leaving less than an hour before the first waves reach Crescent City at midnight. Newport, Oregon: 4 campers killed on a beach. Crescent City: first 3 waves arrive, 4th wave hits at nearly 21 feet.
04
1964–1967: The earthquake and tsunami prompt immediate review of warning infrastructure. In 1967, NOAA establishes the West Coast and Alaska Tsunami Warning Center in Palmer, Alaska. Crescent City installs tsunami sirens — now tested on the first Tuesday of every month. The most tsunami-aware community on the California coast was shaped by the night it wasn't warned in time.
Human Decisions
What went right
Earth Magazine's analysis of the event noted that authorities credited three factors for keeping the death toll low given the earthquake's extraordinary magnitude: sparse population in the most affected Alaskan areas, wood-frame building construction, and the Good Friday holiday — which meant schools and offices were empty when the earthquake struck late in the afternoon. Had the earthquake occurred on a regular weekday with full occupancy, the death toll would have been dramatically higher.
The Seismic Sea Wave Warning System issued a first advisory 90 minutes after the earthquake and a formal tsunami warning 3 hours after. For communities outside Alaska — which had hours before the waves arrived — these warnings enabled some evacuation. The University of Delaware study of warning responses found that communities where officials received and distributed warnings early enough had significantly lower casualties than those where warnings were delayed or dismissed.
Crescent City is now considered one of the most tsunami-prepared communities in the United States. Monthly siren tests, tsunami hazard zone maps on buildings, high-water marks posted throughout downtown as historical markers, and a walking tour of the 1964 damage zone all contribute to a community culture where tsunami risk is normal awareness, not abstract fear.
What went wrong
The Redwood Coast Tsunami Work Group's analysis documented that California's Civil Defense received the tsunami warning at 9:30 PM but did not issue alerts to counties until 11:08 PM — leaving less than an hour for coastal evacuation before midnight arrival. The warning infrastructure existed; the communication chain between state and county was the bottleneck that cost time and lives.
The Active NorCal account of Crescent City noted that residents said "many of the warnings that had been given in the past didn't materialize" — tsunami warning fatigue played a role. When the first waves were small, it seemed the risk had passed. The deaths that followed were mostly people who had survived the first three waves and gone back downtown. Tsunami behavior — variable wave trains with potentially larger later waves — was not widely understood by the public in 1964.
For Valdez, Seward, Whittier, and Chenega, the earthquake itself was the only warning. Local tsunamis generated by underwater landslides arrived within 2–9 minutes of the shaking — far faster than any communication system could have operated. The University of Delaware study confirmed: "the waves arrived too soon for any warning to be effective." No warning center exists to serve this scenario. Only personal knowledge — understanding that strong, prolonged shaking near the coast means move to high ground immediately — can address it.
The compound effect
The 1964 event produced two distinct tsunami disasters: a local disaster in Alaska, where no warning was possible, and a distant disaster in California and Oregon, where hours of warning were available but not fully used. The Alaskan deaths represent the irreducible danger of living near a subduction zone — the lesson is to move to high ground the moment you feel sustained strong shaking, before any official warning arrives. The Crescent City deaths represent a preventable outcome: people who knew a warning had been issued, saw waves that seemed small, and went back to a zone they had been warned to leave. The rule that would have saved them is simple: after a tsunami warning, do not return to the coast until the all-clear is issued. The first wave is never confirmed to be the last.
What Changed
In direct response to the 1964 event, the U.S. government established the West Coast and Alaska Tsunami Warning Center at Palmer, Alaska, in 1967 — now called the National Tsunami Warning Center (NTWC). The NTWC provides tsunami warnings for Alaska, Canada, and the contiguous U.S. coasts within minutes of a major earthquake, compared to the hours-long process that characterized 1964. The NOAA Science on a Sphere documentation confirms that today's warning centers can issue alerts within minutes and produce wave propagation forecasts showing exactly where waves will arrive and when.
Crescent City's response to 1964 — rebuilding with tsunami awareness embedded in community culture — stands as a model for coastal preparedness. The monthly siren test, the high-water markers on surviving buildings, and the walking tour of the damage zone maintain public awareness in a way that no pamphlet can. The NPR account of Crescent City's 40th anniversary notes that the sirens that didn't exist in 1964 are now tested every month — and that the community takes them seriously because they remember what happened when they weren't there.
The 1964 event is the foundation of Pacific Coast tsunami preparedness. Every coastal community in California, Oregon, and Washington has posted tsunami hazard zones, evacuation routes, and assembly areas that exist because of what happened in Crescent City on March 28, 1964. The warning system that today can reach every cell phone on the Pacific Coast within minutes of a major subduction zone earthquake was built on the lesson that the 1964 system was not fast enough, and that people who don't understand tsunami behavior will go back into danger zones when they shouldn't.
If It Happened Today
What You Can Do Now
If you live, work, or visit near the Pacific Coast, the Pacific Northwest, or any U.S. coastline in a seismically active zone, these rules apply directly to you.
For communities near a subduction zone, the earthquake is the tsunami warning. There is no time for an official alert before locally generated waves arrive. If you are on the coast and feel strong shaking lasting 20 seconds or more, do not wait for a siren or an alert. Move to high ground immediately. This rule, if followed by everyone in coastal Alaska in 1964, would have saved most of the 106 who died in that state.
Tsunami preparedness guideMost of the Crescent City deaths were people who survived the first three waves and returned downtown. The rule is absolute: after a tsunami warning, do not return to the hazard zone until an all-clear is officially issued by NOAA or local emergency management. The apparent end of wave activity is not an all-clear. Tsunamis arrive in sets that can continue for hours with variable amplitudes.
Tsunami safety rulesPacific Coast states publish detailed tsunami inundation maps. Your county emergency management office has them. Tsunami evacuation route signs are posted throughout coastal communities. Know which zone you live or work in, where the nearest high ground is, and how long it takes to walk there. This information should be looked up now — in good weather, with no urgency — so the decision is already made when the shaking starts.
Find your tsunami zoneThe ocean pulling back dramatically from shore is a warning sign that a tsunami wave is drawing water ahead of its arrival. In Valdez in 1964, witnesses described the water retreating before the surge returned. This phenomenon — the "drawback" — is sometimes the only observable warning before a wave. If you see the ocean recede suddenly and dramatically, exposing seafloor that is normally submerged, move to high ground immediately. Do not go to the water's edge to look.
Tsunami warning signsThe 1964 warning chain was too slow to save lives in some communities. Today's system is dramatically faster, but only reaches you if your alerts are enabled. Wireless Emergency Alerts on your phone, NOAA Weather Radio, and your county's coastal warning siren system together create the redundancy that no single channel can provide. Check that Wireless Emergency Alerts are enabled in your phone settings. Know where the nearest coastal siren is. Test day in Crescent City is the first Tuesday of every month.
Set up your alert systemsNext step
The tsunami preparedness guide covers inundation zone identification, the earthquake-as-warning rule, evacuation routes, the all-clear protocol, and the specific behavioral rules that save lives when official warnings can't arrive fast enough.
Tsunami preparedness guideSources