Reviewed by USGSAlaska15y ago
M2.7 earthquake 17 km ESE of Atka, Alaska
Wednesday, November 23, 2011, 04:00:06 UTC · 52.114°N, 173.980°W
A magnitude 2.7 earthquake struck 17 km ESE of Atka, Alaska on Wednesday, November 23, 2011, 04:00:06 UTC, at a depth of 83.5 km (intermediate).
- Magnitude
- 2.7
- Minor · m
- Depth
- 84 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
132 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
84 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 2 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M2.7 on December 23, 2011. 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 834 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.61957 Atka, Alaska EarthquakeMarch 9, 1957 · 132 km SW of this epicenter
- 8.01986 Atka, Alaska EarthquakeMay 7, 1986 · 86 km SW of this epicenter
- 7.977 km WSW of Adak, AlaskaJune 10, 1996 · 258 km W of this epicenter
- 7.65 km WNW of Adak, AlaskaFebruary 14, 1905 · 188 km W of this epicenter
- 7.4133 km WNW of Nikolski, AlaskaApril 18, 1916 · 267 km NE of this epicenter
- 7.388 km WSW of Adak, AlaskaJuly 7, 1929 · 268 km W of this epicenter
- 7.346 km SSW of Adak, AlaskaJune 10, 1996 · 209 km W of this epicenter
- 7.3Fox Islands, Aleutian Islands, AlaskaJune 24, 2011 · 147 km E of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 12 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 2 recorded deaths. The most severe:
- 1957M8.6
Alaska
9 Mar 1957 · 132 km away
2 deathsSevere damage ($5–24M)tsunami
- 1986M8.0
Aleutian Islands: Adak
7 May 1986 · 86 km away · intensity VI
Moderate damage ($1–5M)tsunami
- 1901M7.8
Aleutian Islands: Fox Islands
31 Dec 1901 · 217 km away
Limited damage (under $1M)tsunami
- 1996M7.9
Andreanof Islands
10 Jun 1996 · 258 km away · intensity VI
tsunami
- 1907M7.8
Aleutian Islands
2 Sep 1907 · 293 km away
- 1916M7.5
Aleutian Islands: Fox Islands
18 Apr 1916 · 299 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.