M5.6 earthquake 99 km S of Attu Station, Alaska
A magnitude 5.6 earthquake struck 99 km S of Attu Station, Alaska on Fri, Jul 30, 1971, 10:18 AM GMT+12 (22:18 UTC), 26 km (16 mi) below the surface.
Map
Where this earthquake was located, with the others nearby. Select one for its page.
The earthquake
- Magnitude
- 5.6 (Mw, moment), moderate
- Magnitude from
- ISC-GEM global catalog
- Local time
- UTC
- 1971-07-29 22:18:19 UTC
- Depth
- 25.7 km (16.0 mi), shallow
- Epicenter
- 51.953° N, 173.297° E
- 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 |
|---|---|---|---|
| 5.63 | Mw, moment | ISC-GEM global catalog | Preferred · Final · ±0.2 |
| 5.6 | Ms, surface-wave | USGS historic United States catalog | Final |
What happened
The USGS’s account of the effects of this earthquake.
Maximum observed Modified Mercalli Intensity (MMI) I
From the USGS event page for iscgem782989. 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.
- Magnitude uncertainty
- ±0.20
- Depth from
- From location
Nearby
Within 100 km, magnitude 2.6 and up: 0 in the 60 days after this one and 2 in the 30 days before it.
Before
Earthquakes todayAlaska earthquakesLive radar here
Sources
From the USGS Earthquake Hazards Program and its partner networks, event iscgem782989 (also filed as ushis3167). Read Fri, Oct 2, 2026, 8:59 PM UTC.