Alaska earthquakes

M4.8 earthquake 138 km WSW of Adak, Alaska

A magnitude 4.8 earthquake struck 138 km WSW of Adak, Alaska on Fri, Aug 4, 2017, 5:07 PM HADT (02:07 UTC), 10 km (6 mi) below the surface.

A larger quake followed: M5.1 125 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: 4.8 (mb, body-wave), light
Magnitude from: USGS National Earthquake Information Center
Local time: Fri, Aug 4, 2017, 5:07 PM HADT
UTC: 2017-08-05 02:07:45 UTC
Depth: 10.0 km (6.2 mi), shallow
Epicenter: 51.510° N, 178.550° W
Region: Alaska
Strongest shaking: IV, light shaking
PAGER alert: Green
Tsunami flag: Yes: a large quake in an oceanic region
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
4.8	mb, body-wave	USGS National Earthquake Information Center	Preferred · Reviewed · ±0.032 · 309 stations
4.8	mb, body-wave	Alaska Earthquake Center	Preliminary
5.0	ML, local (Richter)	NOAA National Tsunami Warning Center	Reviewed · 9 stations

Tsunami

The USGS flags a quake this large in an oceanic region. The flag does not mean a tsunami happened; the tsunami warning centers decide that, and their messages are below when they issued any.

Current tsunami warnings: tsunami.gov. Warnings in force in the US also appear on our alerts pages.

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
Map: Automatic

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

Did you feel it?

No one has reported feeling this quake to the USGS.

Estimated impact

The USGS PAGER system estimates deaths and economic losses from the shaking and the population and buildings exposed to it.

Alert level: Green: little or no damage or loss of life expected

Deaths: estimated chance of each range
Range	Chance
Under 1	69%
1 to 10	29%
10 to 100	2%
100 to 1,000	Under 1%
1,000 to 10,000	Under 1%
10,000 to 100,000	Under 1%
100,000 to 10,000,000	Under 1%

Economic losses: estimated chance of each range
Range, million USD	Chance
Under 1	65%
1 to 10	30%
10 to 100	4%
100 to 1,000	Under 1%
1,000 to 10,000	Under 1%
10,000 to 100,000	Under 1%
100,000 to 10,000,000	Under 1%

How well it is located

Reviewed by a seismologist.

Location uncertainty: About 5.2 km horizontally, 1.8 km in depth
Magnitude uncertainty: ±0.03
Depth from: Operator assigned
Station coverage gap: 92°
Stations used: 151

Nearby

Within 100 km, magnitude 1.8 and up: at least 199 in the 60 days after this one and at least 200 in the 30 days before it.

After

The first 60 of at least 199.

Before

Earthquakes today Alaska earthquakes Live radar here

Sources

From the USGS Earthquake Hazards Program and its partner networks, event us2000a508 (also filed as ak16437689, at00ou6wkx, ak0179ywurz5). Read Fri, Oct 2, 2026, 11:30 AM UTC.