Alaska Earthquake Triggers Tsunami Warning—Cancelled Quickly, But Is Rooted In A Deadly Past

Thursday, July 17, 2025, 18:54

A 7.3 quake off the Alaska Peninsula triggers tsunami alerts-but no waves
A powerful 7.3-magnitude earthquake recently struck near Sand Point, Popof Island, off the southern coast of Alaska. It occurred at a shallow depth of 10 km and immediately prompted tsunami warnings across 700 miles of coastline-from southwest of Homer to Unimak Pass.

But within a few hours, the warnings were downgraded and eventually cancelled. No significant tsunami waves were observed. For locals, it was more a drill than a disaster-a scenario Alaska knows all too well.

Why Alaska Quakes Are Frequent

Alaska is no stranger to seismic activity because of its place on the Pacific "Ring of Fire"-a massive horseshoe-shaped zone of tectonic unrest.

The Pacific Plate pushes beneath the North American Plate at the Alaska-Aleutian subduction zone
These plate movements generate frequent and powerful earthquakes
Alaska records thousands of earthquakes each year, many too small to feel

This geological setup makes the region one of the most earthquake-prone areas in the world.

Recent Close Calls That Sounded the Alarm

While the latest quake caused no tsunami, it's not the first time a big quake in Alaska led to warnings that were later cancelled:

July 2020 - 7.8 Magnitude Near Perryville

Triggered full tsunami warnings along southern Alaska
Communities evacuated to higher ground
Only minor waves were recorded (under 1 foot)

October 2020 - 7.6 Magnitude Near Sand Point

Occurred in nearly the same region
Issued a tsunami advisory, not a warning
Again, no destructive waves followed

July 2021 - 8.2 Magnitude Off Chignik

The strongest U.S. earthquake in more than 50 years
Set off widespread tsunami warnings
Waves were less than 0.5 metres; warnings were cancelled soon after

January 2018 - 7.9 Magnitude In The Gulf Of Alaska

Alerts were issued as far south as California
Because it was a strike-slip earthquake (horizontal movement), no tsunami formed
In each case, the initial fear of a massive wave faded with data. But the response-sirens, evacuations, alerts-remains swift and serious.

The Quake That Changed Everything: 1964

Alaska's caution comes from hard-learned experience.

On March 27, 1964, a 9.2-magnitude earthquake struck near Prince William Sound. It remains the second most powerful earthquake ever recorded.

Massive tsunamis followed, wiping out entire towns like Valdez and Seward
The waves reached as far as Hawaii and the U.S. West Coast
Over 130 people died, most due to tsunami waves rather than the shaking itself

That tragedy redefined how Alaska and the rest of the Pacific prepares for tsunamis. Today's alert systems, drills, and community readiness all trace back to lessons learned in 1964.

How Tsunami Warnings Actually Work

Not every quake triggers a tsunami. But when one might, agencies act fast.

Computer models analyse the quake's depth, location, and magnitude
DART buoys in deep ocean and tide gauges near shore track real-time sea level changes
If data shows rising water, tsunami alerts are issued immediately

Two key types of alerts:

Tsunami Warning: A dangerous wave is expected. Immediate evacuation advised.

Tsunami Advisory: Strong currents and wave activity possible, but no large-scale flooding expected

Even if the waves don't arrive, it's better to move than regret staying.

Be Prepared, Don't Panic

The recent 7.3-magnitude quake near Sand Point ended quietly-but it won't be the last. For Alaska, where seismic activity is a daily possibility, readiness is routine.

People living along its rugged coastlines know the drill: