M4.7 earthquake 87 km SW of Atka, Alaska

A magnitude 4.7 earthquake struck 87 km SW of Atka, Alaska on Fri, Jan 17, 2020, 4:13 AM HAST (14:13 UTC), 42 km (26 mi) below the surface.

A larger quake followed: M5.0 119 km SSW of Atka, 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
4.7	Mww, W-phase moment	USGS National Earthquake Information Center	Preferred · Reviewed · ±0.093 · 11 stations
5.0	ML, local (Richter)	Alaska Earthquake Center	Preliminary
4.8	Mwr, regional moment	USGS National Earthquake Information Center	Moment tensor · Reviewed

1 person reported to the USGS what they felt; the strongest reported shaking was III, weak shaking.

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

Reviewed by a seismologist.

Within 100 km, magnitude 1.7 and up: 151 in the 60 days after this one and 54 in the 30 days before it.

The first 60 of 151.

From the USGS Earthquake Hazards Program and its partner networks, event us700071nr (also filed as ak020scjtpj). Read Thu, Oct 1, 2026, 12:32 PM UTC.