Earthquake.now

M5.3 Earthquake near Unalaska, United States — 27 July 2025, 22:47 UTC

A moderate earthquake of magnitude 5.3 was recorded near Unalaska, United States on , with an epicentre 29 km east-southeast of Unalaska, at a focal depth of 75.0 km. It ranked as the 15th strongest of 7999 earthquakes recorded in the United States in the preceding 30 days.

5.3 Moderate

Time (UTC): 2025-07-27 22:47:05

Time (your timezone): —

Magnitude: 5.3 (moderate)

Focal depth: 75.0 km (intermediate)

Epicentre: 53.7450, -166.1370

Location: 29 km ESE of Unalaska, Alaska

Country: United States

USGS link to NOAA tsunami information: Available

Review status: Reviewed

Source: USGS event page

How strong was this earthquake?

Moderate earthquakes can damage poorly built or unreinforced structures near the epicentre, while well-engineered buildings typically escape serious harm. Shaking is often strong enough to wake sleeping residents over a wide area.

A magnitude 5.3 earthquake radiates roughly 1,344 tons of TNT equivalent in seismic energy.

The USGS assigns this earthquake a significance score of 435, which is below the USGS threshold of more than 600 for its significant-earthquake list. The ranking combines magnitude with available Did You Feel It responses and PAGER alert level; it is not a direct measurement of damage.

What the magnitude scale actually measures →

When it happened locally

That is about 11:42 local solar time at the epicentre, during the morning.

This event was deeper than 96% of the 156,123 earthquakes recorded in the United States in our catalogue and stronger than 100% of them.

Where was the epicentre?

The epicentre was located at 53.7450, -166.1370 — 29 km east-southeast of Unalaska. The closest other recorded event was a magnitude 2.0 earthquake 11 km south of here on 03 September 2026.

The nearest other settlement in our records is Akutan (169 km southeast).

Why the 75 km depth matters

At 75 km this was an intermediate-depth earthquake. Energy from events at this depth spreads out before it reaches the surface, which usually means weaker shaking near the epicentre than a shallow quake of the same magnitude, but shaking felt across a wider area.

This catalogue does not ingest eyewitness responses, so it cannot confirm where this earthquake was felt. Based on magnitude alone, an event this size can be felt widely and may cause minor local damage. Its intermediate depth normally reduces peak shaking near the epicentre compared with a shallow event of the same magnitude.

Read more on how focal depth changes what you feel →

What does the tsunami information flag mean?

The USGS event record links to NOAA tsunami information because this was a large event in an oceanic region. That link flag does not mean a tsunami occurred or that a warning is active. Check tsunami.gov and instructions from your local authority for the current status of your coastline.

How earthquakes generate tsunamis, and what the alert levels mean →

Aftershocks and local seismic history

28 further earthquakes have been recorded within about 150 km of the epicentre in the seven days after this event, the largest of them magnitude 3.6.

35 earthquakes of magnitude 4 or above have been logged within roughly 200 km of this epicentre in our catalogue. The strongest was a magnitude 5.6 event near Unalaska on 26 January 2025. This M5.3 event released about 2.8 times less energy than that event.

511 earthquakes have been recorded within 100 km of this epicentre in the past year, 60 of them in the past 30 days.

How long aftershock sequences last, and how large they get →

Where this event sits in the record

This earthquake is part of the July 2025 worldwide record, and of earthquakes in the United States during July 2025. Browse the full monthly archive to compare periods.

Nearest recorded earthquakes to this epicentre

Other recent earthquakes in the United States

All recorded earthquakes in the United States →

Other magnitude 5 earthquakes worldwide

All magnitude 5 earthquakes →

Questions about this earthquake

How strong was the earthquake near Unalaska?

It measured magnitude 5.3 — a moderate earthquake. A magnitude 5.3 earthquake radiates roughly 1,344 tons of TNT equivalent in seismic energy.

How deep was the earthquake near Unalaska?

The focus was 75 km below the surface, which counts as intermediate.

Was the Unalaska earthquake felt at the surface?

At magnitude 5.3 and a focal depth of 75 km, the depth spreads the energy out, so shaking is weaker overhead but reaches further.

When did the earthquake near Unalaska happen?

27 July 2025 at 22:47 UTC.

Was there a tsunami?

The USGS record carries a link to NOAA tsunami information for this event. That is not a warning: check your regional tsunami warning centre for any live alert.

Have there been aftershocks?

28 further earthquakes have been recorded within about 150 km of the epicentre in the seven days after this event, the largest of them magnitude 3.6.

How often do earthquakes happen near Unalaska?

35 earthquakes of magnitude 4 or above have been logged within roughly 200 km of this epicentre in our catalogue. The strongest was a magnitude 5.6 event near Unalaska on 26 January 2025. This M5.3 event released about 2.8 times less energy than that event.