M4.5 earthquake 80 km S of Perryville, Alaska

A magnitude 4.5 earthquake struck 80 km S of Perryville, Alaska on Thu, Jul 23, 2020, 11:17 PM AKDT (07:17 UTC), 42 km (26 mi) below the surface.

A larger quake followed: M5.6 44 km SSE of Sand Point, 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
4.5	Mwr, regional moment	USGS National Earthquake Information Center	Preferred · Reviewed · ±0.066 · 22 stations
4.4	ML, local (Richter)	Alaska Earthquake Center	Preliminary

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: at least 202 in the 60 days after this one and at least 200 in the 30 days before it.

The first 60 of at least 202.

From the USGS Earthquake Hazards Program and its partner networks, event us6000b389 (also filed as ak0209gsz8kx). Read Thu, Oct 1, 2026, 2:15 PM UTC.