M3.9 earthquake 44 km SSE of Old Harbor, Alaska
A magnitude 3.9 earthquake struck 44 km SSE of Old Harbor, Alaska on Mon, Jul 21, 1975, 2:35 PM GMT-9 (23:35 UTC), 21 km (13 mi) below the surface.
A larger quake followed: M4.9 92 km SE of Old Harbor, Alaska. This one was a foreshock.
Map
Where this earthquake was located, with the others nearby. Select one for its page.
The earthquake
- Magnitude
- 3.9 (mb), minor
- Local time
- UTC
- 1975-07-21 23:35:08 UTC
- Depth
- 21.0 km (13.0 mi), shallow
- Epicenter
- 56.822° N, 153.074° W
- Region
- Alaska
- Tsunami flag
- No
- Status
- Reviewed by a seismologist
Did you feel it?
No one has reported feeling this quake to the USGS.
How well it is located
Reviewed by a seismologist.
- Stations used
- 12
Nearest places
Distance and direction from each place to the epicenter, with its forecast.
Nearby
Within 100 km, magnitude 1.5 and up: 3 in the 60 days after this one and 0 in the 30 days before it.
After
Earthquakes todayAlaska earthquakesLive radar here
Sources
From the USGS Earthquake Hazards Program and its partner networks, event usp0000c47. Read Tue, Sep 22, 2026, 8:29 AM UTC.