Reviewed by USGSAlaska14y ago
M4.4 earthquake 148 km E of Atka, Alaska
Friday, May 25, 2012, 06:23:29 UTC · 52.335°N, 172.033°W
A magnitude 4.4 earthquake struck 148 km E of Atka, Alaska on Friday, May 25, 2012, 06:23:29 UTC, at a depth of 78.5 km (intermediate).
- Magnitude
- 4.4
- Light · mb
- Depth
- 79 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
60 tons of TNT
That is about 1/251 of the Hiroshima bomb. A magnitude 5.0 releases about 8 times more energy.
Tectonic setting
131 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
79 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 M4.2 on June 16, 2012. 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 809 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 · 263 km W of this epicenter
- 8.01986 Atka, Alaska EarthquakeMay 7, 1986 · 209 km SW of this epicenter
- 7.8234 km SSW of Nikolski, AlaskaMarch 7, 1929 · 222 km SE of this epicenter
- 7.4133 km WNW of Nikolski, AlaskaApril 18, 1916 · 153 km NE of this epicenter
- 7.3Fox Islands, Aleutian Islands, AlaskaJune 24, 2011 · 34 km SE of this epicenter
- 7.158 km WNW of Atka, AlaskaFebruary 28, 1970 · 196 km W of this epicenter
- 7.135 km SW of Nikolski, AlaskaMarch 11, 1957 · 196 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 · 263 km away
2 deathsSevere damage ($5–24M)tsunami
- 1986M8.0
Aleutian Islands: Adak
7 May 1986 · 209 km away · intensity VI
Moderate damage ($1–5M)tsunami
- 1901M7.8
Aleutian Islands: Fox Islands
31 Dec 1901 · 120 km away
Limited damage (under $1M)tsunami
- 1907M7.8
Aleutian Islands
2 Sep 1907 · 159 km away
- 1929M7.8
Aleutian Islands: Fox Islands
7 Mar 1929 · 204 km away · intensity V
tsunami
- 1916M7.5
Aleutian Islands: Fox Islands
18 Apr 1916 · 174 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.