Alaska earthquakes

M3.8 earthquake 23 km SSW of Tanacross, Alaska

A magnitude 3.8 earthquake struck 23 km SSW of Tanacross, Alaska on Sun, Apr 4, 2021, 9:09 AM AKDT (17:09 UTC), 3 km (2 mi) below the surface.

Tok forecast More in Alaska

Map

Where this earthquake was located, with the others nearby. Select one for its page.

Open the live map with earthquakes

The earthquake

Magnitude: 3.8 (ML, local (Richter)), minor
Magnitude from: Alaska Earthquake Center
Local time: Sun, Apr 4, 2021, 9:09 AM AKDT
UTC: 2021-04-04 17:09:21 UTC
Depth: 2.9 km (1.8 mi), shallow
Epicenter: 63.190° N, 143.523° W
Region: Alaska
Felt reports: 3
Strongest shaking: IV, light shaking
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
3.8	ML, local (Richter)	Alaska Earthquake Center	Preferred · Preliminary
3.6	Mwr, regional moment	USGS National Earthquake Information Center	Reviewed · ±0.043 · 51 stations
3.9	Mi	NOAA Pacific Tsunami Warning Center	First automatic solution · Reviewed · 4 stations

Shaking

The USGS ShakeMap: shaking estimated from seismic stations and the quake’s size, on the Modified Mercalli intensity scale.

Strongest estimated: IV, light shaking
Peak ground acceleration: 881.0% of gravity
Peak ground velocity: 2.3 cm/s
Map: Automatic

USGS ShakeMap: estimated shaking intensity around the epicenter — Estimated shaking intensity. Map: USGS ShakeMap.

Did you feel it?

3 people reported to the USGS what they felt; the strongest reported shaking was II, weak shaking.

Fault motion and ground failure

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

Faulting: Reverse (thrust)
Moment magnitude: 3.6 Mwr
Nodal plane 1: Strike 339°, dip 35°, rake 118°
Nodal plane 2: Strike 126°, dip 59°, rake 72°

How well it is located

Reviewed by a seismologist.

Stations used: 233

Nearest places

Distance and direction from each place to the epicenter, with its forecast.

Nearby

Within 100 km, magnitude 1.5 and up: 16 in the 60 days after this one and 7 in the 30 days before it.

After

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event ak0214bqoyto (also filed as pt21094001, us6000dyz2). Read Fri, Oct 2, 2026, 7:10 AM UTC.