Alaska earthquakes

M5.0 earthquake 124 km WSW of Adak, Alaska

A magnitude 5.0 earthquake struck 124 km WSW of Adak, Alaska on Sat, Apr 20, 2019, 9:31 PM HADT (06:31 UTC), 53 km (33 mi) below the surface.

A larger quake followed: M6.0 127 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.

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The earthquake

Magnitude: 5.0 (Mww, W-phase moment), moderate
Magnitude from: USGS National Earthquake Information Center
Local time: Sat, Apr 20, 2019, 9:31 PM HADT
UTC: 2019-04-21 06:31:36 UTC
Depth: 53.4 km (33.2 mi), shallow
Epicenter: 51.462° N, 178.308° W
Region: Alaska
Tsunami flag: No
Status: Reviewed by a seismologist

Magnitude estimates

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
5.0	Mww, W-phase moment	USGS National Earthquake Information Center	Preferred · Reviewed · ±0.061 · 26 stations
5.02	Mw, moment	ISC-GEM global catalog	Final · ±0.1
5.2	ML, local (Richter)	Alaska Earthquake Center	Preliminary

Did you feel it?

No one has reported feeling this quake to the USGS.

Fault motion and ground failure

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

Faulting: Oblique reverse
Moment magnitude: 5.0 Mww
Nodal plane 1: Strike 274°, dip 41°, rake 121°
Nodal plane 2: Strike 55°, dip 56°, rake 66°

How well it is located

Reviewed by a seismologist.

Location uncertainty: About 7.5 km horizontally, 4.9 km in depth
Magnitude uncertainty: ±0.06
Depth from: From location
Station coverage gap: 126°
Stations used: 175

Nearby

Within 100 km, magnitude 2.0 and up: 109 in the 60 days after this one and 55 in the 30 days before it.

After

The first 60 of 109.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us700039xa (also filed as ak01953oeufh, iscgem615412577). Read Thu, Oct 1, 2026, 8:22 PM UTC.