Alaska earthquakes

M5.8 earthquake 76 km SSE of Adak, Alaska

A magnitude 5.8 earthquake struck 76 km SSE of Adak, Alaska on Fri, Jul 25, 1986, 12:01 AM HADT (09:01 UTC), 33 km (21 mi) below the surface.

A larger quake followed: M5.9 79 km S 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: 5.8 (Mw, moment), moderate
Magnitude from: USGS National Earthquake Information Center
Local time: Fri, Jul 25, 1986, 12:01 AM HADT
UTC: 1986-07-25 09:01:32 UTC
Depth: 33.0 km (20.5 mi), shallow
Epicenter: 51.247° N, 176.173° 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
5.8	Mw, moment	USGS National Earthquake Information Center	Preferred · Reviewed
5.8	Mw, moment	ISC-GEM global catalog	Final · ±0.1
5.82	Mw, moment	USGS historic United States catalog	Final
5.8	Mwc, centroid moment	Global CMT project	Preliminary

What happened

The USGS’s account of the effects of this earthquake.

Felt (IV) on Adak. CENTROID, MOMENT TENSOR (HRV) Data Used: GDSN L.P.B.: 17S, 39C Centroid Location: Origin Time 09:01:34.7 0.3 Lat 51.21N 0.03 Lon 175.82W 0.07 Dep 25.0 2.3 Half-duration 3.0 Moment Tensor; Scale 10**24 D-CM Mrr=3.94 0.11 Mtt=-3.29 0.13 Mff=-0.65 0.12 Mrt=3.87 0.46 Mrf=2.26 0.36 Mtf=-1.97 0.14 Principal Axes: (T) Val=5.90 Plg=66 Azm=328 (N) Val=0.40 Plg=1 Azm=61 (P) Val=-6.30 Plg=24 Azm=151 Best Double Couple:Mo=6.1*10**24 NP1:Strike=244 Dip=21 Slip=94 NP2:Strike=60 Dip=69 Slip=89

Maximum observed Modified Mercalli Intensity (MMI) IV

From the USGS event page for usp0002wg7. U.S. Geological Survey text and figures are in the public domain.

Did you feel it?

No one has reported feeling this quake to the USGS.

How well it is located

Reviewed by a seismologist.

Depth from: OPERATOR_ASSIGNED

Nearby

Within 100 km, magnitude 2.8 and up: 22 in the 60 days after this one and 21 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 usp0002wg7 (also filed as gcmtb072586a, ushis3989, gcmt19860725090132, iscgem491656). Read Thu, Oct 1, 2026, 7:36 PM UTC.