M4.0 earthquake 92 km SW of Adak, Alaska

A magnitude 4.0 earthquake struck 92 km SW of Adak, Alaska on Wed, Sep 12, 2018, 8:57 AM HADT (17:57 UTC), 42 km (26 mi) below the surface.

A larger quake followed: M4.8 126 km WSW of Adak, 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 · ±0.076 · 46 stations
4.0	mb, body-wave	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: at least 199 in the 60 days after this one and at least 200 in the 30 days before it.

The first 60 of at least 199.

From the USGS Earthquake Hazards Program and its partner networks, event us2000hdj9 (also filed as ak018bq0i63y). Read Sat, Oct 3, 2026, 1:21 AM UTC.