Reviewed by USGSAlaska14y ago
M3.3 earthquake 129 km W of Nikolski, Alaska
Friday, August 10, 2012, 02:22:48 UTC · 52.805°N, 170.769°W
A magnitude 3.3 earthquake struck 129 km W of Nikolski, Alaska on Friday, August 10, 2012, 02:22:48 UTC, at a depth of 216.8 km (intermediate).
- Magnitude
- 3.3
- Minor · ml
- Depth
- 217 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
1 tons of TNT
That is about 1/11,203 of the Hiroshima bomb. A magnitude 5.0 releases about 355 times more energy.
Tectonic setting
155 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
217 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 3 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M3.7 on August 22, 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 684 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.8234 km SSW of Nikolski, AlaskaMarch 7, 1929 · 222 km S of this epicenter
- 7.881 km E of Nikolski, AlaskaJuly 2, 1965 · 210 km E of this epicenter
- 7.4133 km WNW of Nikolski, AlaskaApril 18, 1916 · 71 km N of this epicenter
- 7.3Fox Islands, Aleutian Islands, AlaskaJune 24, 2011 · 111 km SW of this epicenter
- 7.158 km WNW of Atka, AlaskaFebruary 28, 1970 · 282 km W of this epicenter
- 7.135 km SW of Nikolski, AlaskaMarch 11, 1957 · 107 km E of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 13 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1901M7.8
Aleutian Islands: Fox Islands
31 Dec 1901 · 152 km away
Limited damage (under $1M)tsunami
- 1965M6.5
Aleutian Islands: Fox Islands
2 Jul 1965 · 217 km away
Limited damage (under $1M)tsunami
- 1917M7.9
Alaska Peninsula
31 May 1917 · 246 km away · intensity V
- 1902M7.8
Aleutian Islands: Fox Islands
1 Jan 1902 · 225 km away
- 1907M7.8
Aleutian Islands
2 Sep 1907 · 74 km away
- 1929M7.8
Aleutian Islands: Fox Islands
7 Mar 1929 · 208 km away · intensity V
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.