M4.0 earthquake 107 km SW of Nikolski, Alaska

A magnitude 4.0 earthquake struck 107 km SW of Nikolski, Alaska on Mon, Aug 3, 2020, 5:45 PM HADT (02:45 UTC), 35 km (22 mi) below the surface.

A larger quake followed: M5.5 129 km SSW of Nikolski, 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 · ±0.299 · 3 stations
3.3	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: 37 in the 60 days after this one and 18 in the 30 days before it.

From the USGS Earthquake Hazards Program and its partner networks, event us6000b90u (also filed as ak0209yx32a1). Read Mon, Oct 5, 2026, 9:26 AM UTC.