Reviewed by USGSAlaska5y ago
M3.6 earthquake 38 km SE of Akutan, Alaska
Monday, September 13, 2021, 14:02:49 UTC · 53.899°N, 165.346°W
A magnitude 3.6 earthquake struck 38 km SE of Akutan, Alaska on Monday, September 13, 2021, 14:02:49 UTC, at a depth of 75.7 km (intermediate).
- Magnitude
- 3.6
- Minor · mb
- Depth
- 76 km
- Intermediate
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- —
- No ShakeMap
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquake
In context
How big was it, and why here?
Energy released
4 tons of TNT
That is about 1/3,975 of the Hiroshima bomb. A magnitude 5.0 releases about 126 times more energy.
Tectonic setting
127 km
from the nearest mapped plate boundary, between the North American and Pacific plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.
Depth: intermediate
76 km
Intermediate-depth earthquakes usually break inside a plate that is sinking into the mantle. Shaking spreads over a wide area but is gentler at the epicenter than a shallow quake of the same size.
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 has not published any M2.5+ earthquake within 50 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 546 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 · 172 km E of this epicenter
- 7.881 km E of Nikolski, AlaskaJuly 2, 1965 · 182 km SW of this epicenter
- 7.190 km SE of King Cove, AlaskaMay 14, 1948 · 283 km E of this epicenter
- 7.139 km S of Akutan, AlaskaMarch 22, 1957 · 31 km SW of this epicenter
- 7.135 km SW of Nikolski, AlaskaMarch 11, 1957 · 289 km SW of this epicenter
- 7.071 km SE of King Cove, AlaskaMay 30, 1991 · 254 km E of this epicenter
- 7.0203 km SSE of Unalaska, AlaskaAugust 22, 1940 · 194 km S 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 · 172 km away · intensity VI
168 deaths$26 million damagetsunami
- 1965M6.5
Aleutian Islands: Fox Islands
2 Jul 1965 · 175 km away
Limited damage (under $1M)tsunami
- 1917M7.9
Alaska Peninsula
31 May 1917 · 264 km away · intensity V
- 1902M7.8
Aleutian Islands: Fox Islands
1 Jan 1902 · 220 km away
- 1948M7.5
Alaska Peninsula
14 May 1948 · 290 km away
- 1957M7.5
Aleutian Islands: Fox Islands
22 Mar 1957 · 123 km away · intensity V
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.