M2.5 earthquake 136 km SW of Nikolski, Alaska

A magnitude 2.5 earthquake struck 136 km SW of Nikolski, Alaska on Sat, Oct 30, 2021, 2:45 PM HADT (23:45 UTC), 19 km (12 mi) below the surface.

A larger quake followed: M4.2 71 km SW 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
2.5	ML, local (Richter)	USGS National Earthquake Information Center	Preferred · Reviewed · ±0.115 · 10 stations
2.5	ML, local (Richter)	Alaska Earthquake Center	Preliminary

No one has reported feeling this quake to the USGS.

Reviewed by a seismologist.

Within 100 km, magnitude 1.5 and up: 22 in the 60 days after this one and 14 in the 30 days before it.

From the USGS Earthquake Hazards Program and its partner networks, event us6000g9qn (also filed as ak021dxhsuj1). Read Thu, Oct 1, 2026, 5:29 AM UTC.