Reviewed by USGSAlaska5y ago
M2.7 earthquake 41 km N of False Pass, Alaska
Monday, March 15, 2021, 06:19:32 UTC · 55.228°N, 163.394°W
A magnitude 2.7 earthquake struck 41 km N of False Pass, Alaska on Monday, March 15, 2021, 06:19:32 UTC, at a depth of 184.0 km (intermediate).
- Magnitude
- 2.7
- Minor · ml
- Depth
- 184 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 earthquakeDashed circle: 50 km aftershock search area
In context
How big was it, and why here?
Energy released
169 kg of TNT
That is about 1/88,990 of the Hiroshima bomb. A magnitude 5.0 releases about 2,818 times more energy.
Tectonic setting
215 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
184 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 lists 4 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M2.8 on March 26, 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 365 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 · 196 km S of this epicenter
- 7.62020 Sand Point, Alaska EarthquakeOctober 19, 2020 · 251 km E of this epicenter
- 7.454 km SE of Sand Point, AlaskaMay 31, 1917 · 225 km E of this epicenter
- 7.190 km SE of King Cove, AlaskaMay 14, 1948 · 159 km SE of this epicenter
- 7.139 km S of Akutan, AlaskaMarch 22, 1957 · 223 km SW of this epicenter
- 7.071 km SE of King Cove, AlaskaMay 30, 1991 · 136 km SE of this epicenter
- 6.917 km S of Sand Point, AlaskaMay 13, 1993 · 186 km E of this epicenter
- 6.873 km SW of Sand Point, AlaskaJuly 2, 1922 · 145 km E of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 8 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 · 196 km away · intensity VI
168 deaths$26 million damagetsunami
- 1788M8.0
Alaska Peninsula
6 Aug 1788 · 154 km away
tsunami
- 2020M7.6
Alaska
19 Oct 2020 · 251 km away · intensity IX
tsunami
- 1948M7.5
Alaska Peninsula
14 May 1948 · 173 km away
- 1957M7.5
Aleutian Islands: Fox Islands
22 Mar 1957 · 118 km away · intensity V
- 1820
East Aleutian Islands
1 Mar 1820 · 113 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.