M4.0 earthquake 27 km S of Old Harbor, Alaska
A magnitude 4.0 earthquake struck 27 km S of Old Harbor, Alaska on Mon, Jun 20, 1977, 8:32 PM GMT-9 (05:32 UTC), 33 km (21 mi) below the surface.
A larger quake followed: M5.0 72 km SSE 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
- 4.0 (mb), light
- Local time
- UTC
- 1977-06-21 05:32:45 UTC
- Depth
- 33.0 km (20.5 mi), shallow
- Epicenter
- 56.958° N, 153.352° 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.
- Depth from
- OPERATOR_ASSIGNED
- Stations used
- 10
Nearest places
Distance and direction from each place to the epicenter, with its forecast.
Nearby
Within 100 km, magnitude 1.5 and up: 2 in the 60 days after this one and 2 in the 30 days before it.
After
- 3.733 km NE of Larsen Bay, Alaska · 17942 days ago · 36 km deep · 86 km away
- 5.072 km SSE of Old Harbor, Alaska · 17940 days ago · 33 km deep · 52 km away
Before
Earthquakes todayAlaska earthquakesLive radar here
Sources
From the USGS Earthquake Hazards Program and its partner networks, event usp0000pd9. Read Tue, Sep 22, 2026, 10:49 AM UTC.