Reviewed by USGSAlaska5y ago
M3.8 earthquake 106 km SE of King Cove, Alaska
Monday, May 3, 2021, 00:28:57 UTC · 54.283°N, 161.356°W
A magnitude 3.8 earthquake struck 106 km SE of King Cove, Alaska on Monday, May 3, 2021, 00:28:57 UTC, at a depth of 10.0 km (shallow).
- Magnitude
- 3.8
- Minor · mb
- Depth
- 10 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- —
- No ShakeMap
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeDashed circle: 50 km aftershock search area
In context
How big was it, and why here?
Energy released
8 tons of TNT
That is about 1/1,992 of the Hiroshima bomb. A magnitude 5.0 releases about 63 times more energy.
Tectonic setting
78 km
from the nearest mapped plate boundary, between the North American and Pacific plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
10 km
Shallow earthquakes (under 70 km) produce the strongest surface shaking for their size, so they are the ones most likely to cause damage near the epicenter.
Did You Feel It?
Where it was felt
No “Did You Feel It?” reports have been published for this event yet. If you felt it, you can add your report on the USGS website.
I felt it — report to USGS ↗USGS PAGER estimate
Who was exposed to shaking
USGS publishes PAGER impact estimates for significant earthquakes, usually within an hour. No PAGER estimate is available for this event.
After the main event
Aftershocks within 50 km
USGS lists 4 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M4.2 on May 6, 2021. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 379 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.6The 1946 Unimak Island, Alaska EarthquakeApril 1, 1946 · 131 km SW of this epicenter
- 8.21938 Semidi Islands, Alaska EarthquakeNovember 10, 1938 · 227 km NE of this epicenter
- 7.82020 Perryville, Alaska EarthquakeJuly 22, 2020 · 198 km NE of this epicenter
- 7.62020 Sand Point, Alaska EarthquakeOctober 19, 2020 · 117 km E of this epicenter
- 7.454 km SE of Sand Point, AlaskaMay 31, 1917 · 123 km NE of this epicenter
- 7.190 km SE of King Cove, AlaskaMay 14, 1948 · 37 km N of this epicenter
- 7.139 km S of Akutan, AlaskaMarch 22, 1957 · 294 km W of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 10 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 168 recorded deaths. The most severe:
- 1946M8.6
Unimak Island
1 Apr 1946 · 131 km away · intensity VI
168 deaths$26 million damagetsunami
- 2020M7.8
Alaska
22 Jul 2020 · 198 km away · intensity VII
Limited damage (under $1M)tsunami
- 1938M8.2
Alaska
10 Nov 1938 · 233 km away · intensity VI
tsunami
- 2021M8.2
Alaska Peninsula
29 Jul 2021 · 253 km away · intensity VIII
tsunami
- 1788M8.0
Alaska Peninsula
6 Aug 1788 · 83 km away
tsunami
- 2020M7.6
Alaska
19 Oct 2020 · 117 km away · intensity IX
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.