M4.0 earthquake 215 km W of Adak, Alaska

A magnitude 4.0 earthquake struck 215 km W of Adak, Alaska on Sat, Dec 29, 2018, 8:06 PM HAST (06:06 UTC), 170 km (106 mi) below the surface.

A larger quake followed: M4.8 232 km W 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: 39 in the 60 days after this one and 42 in the 30 days before it.

From the USGS Earthquake Hazards Program and its partner networks, event us2000j562 (also filed as ak018gq387r4). Read Fri, Oct 2, 2026, 4:35 AM UTC.