M3.7 earthquake 133 km SSE of Atka, Alaska

A magnitude 3.7 earthquake struck 133 km SSE of Atka, Alaska on Thu, Apr 12, 2018, 2:03 PM HADT (23:03 UTC), 32 km (20 mi) below the surface.

A larger quake followed: M4.0 73 km SSE 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
3.7	mb, body-wave	USGS National Earthquake Information Center	Preferred · Reviewed · ±0.072 · 49 stations
3.3	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: 19 in the 60 days after this one and 16 in the 30 days before it.

From the USGS Earthquake Hazards Program and its partner networks, event us2000dz9c (also filed as ak0184p2j4n9). Read Fri, Oct 2, 2026, 7:46 PM UTC.