M4.0 earthquake 119 km S of Unalaska, Alaska

A magnitude 4.0 earthquake struck 119 km S of Unalaska, Alaska on Sun, Oct 20, 2024, 7:04 PM AKDT (03:04 UTC), 35 km (22 mi) below the surface.

A larger quake followed: M4.5 74 km SSW of Unalaska, Alaska. This one was a foreshock.

Map

Where this earthquake was located, with the others nearby. Select one for its page.

Different scales measure different things and differ by a few tenths. The USGS marks one as preferred, and it is the one this page uses.

Mag.	Scale	Computed by	Notes
4.0	Mwr, regional moment	USGS National Earthquake Information Center	Preferred · Reviewed · ±0.089 · 12 stations
3.7	ML, local (Richter)	Alaska Earthquake Center	Preliminary

The USGS ShakeMap: shaking estimated from seismic stations and the quake’s size, on the Modified Mercalli intensity scale.

No one has reported feeling this quake to the USGS.

How the rock slipped, from the moment tensor, and the USGS estimate of landslides and liquefaction.

Reviewed by a seismologist.

Distance and direction from each place to the epicenter, with its forecast.

Within 100 km, magnitude 1.5 and up: 112 in the 60 days after this one and 122 in the 30 days before it.

The first 60 of 112.

From the USGS Earthquake Hazards Program and its partner networks, event us6000nzzq (also filed as ak024djxckmb). Read Thu, Oct 1, 2026, 5:16 PM UTC.