M4.0 earthquake Alaska Peninsula

A magnitude 4.0 earthquake struck in the Alaska Peninsula on Wed, Jul 22, 2020, 12:04 AM AKDT (08:04 UTC), 44 km (27 mi) below the surface.

A larger quake followed: M5.7 76 km ESE 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
4.0	mb, body-wave	USGS National Earthquake Information Center	Preferred · Reviewed · ±0.122 · 18 stations
3.8	ML, local (Richter)	Alaska Earthquake Center	Preliminary

No one has reported feeling this quake to the USGS.

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 201 in the 60 days after this one and 52 in the 30 days before it.

The first 60 of at least 201.

From the USGS Earthquake Hazards Program and its partner networks, event us7000asxy (also filed as ak0209dif795). Read Sun, Oct 4, 2026, 8:52 PM UTC.