QuakeScout
Magnitude2.5

Reviewed by USGSAlaska14y ago

M2.5 earthquake 115 km ESE of Nikolski, Alaska

Saturday, August 11, 2012, 20:48:34 UTC · 52.386°N, 167.411°W

A magnitude 2.5 earthquake struck 115 km ESE of Nikolski, Alaska on Saturday, August 11, 2012, 20:48:34 UTC, at a depth of 25.6 km (shallow).

Magnitude
2.5
Minor · ml
Depth
26 km
Shallow
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

85 kg of TNT

That is about 1/177,558 of the Hiroshima bomb. A magnitude 5.0 releases about 5,623 times more energy.

Tectonic setting

27 km

from the nearest mapped plate boundary, between the North American and Pacific plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.

Depth: shallow

26 km

Shallow earthquakes (under 70 km) produce the strongest surface shaking for their size, so they are the ones most likely to cause damage near the epicenter.

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 5 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M3.1 on August 25, 2012. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

M31h6h1d3d7d14d30dMainshock M2.5
Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.
  1. 2.5127 km SE of Nikolski, Alaska14y ago · 12 km SE of this epicenter
  2. 3.1134 km SE of Nikolski, Alaska14y ago · 21 km SE of this epicenter
  3. 2.7113 km ESE of Nikolski, Alaska14y ago · 5 km N of this epicenter
  4. 2.7143 km ESE of Nikolski, Alaska14y ago · 41 km E of this epicenter
  5. 2.5145 km ESE of Nikolski, Alaska14y ago · 34 km E of this epicenter

Regional history

Past M5+ earthquakes within 300 km

USGS lists 617 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

  1. 7.8234 km SSW of Nikolski, AlaskaMarch 7, 1929 · 232 km SW of this epicenter
  2. 7.881 km E of Nikolski, AlaskaJuly 2, 1965 · 71 km N of this epicenter
  3. 7.4133 km WNW of Nikolski, AlaskaApril 18, 1916 · 248 km NW of this epicenter
  4. 7.139 km S of Akutan, AlaskaMarch 22, 1957 · 190 km NE of this epicenter
  5. 7.135 km SW of Nikolski, AlaskaMarch 11, 1957 · 125 km W of this epicenter
  6. 7.0203 km SSE of Unalaska, AlaskaAugust 22, 1940 · 132 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. The most severe:

  1. 1901M7.8

    Aleutian Islands: Fox Islands

    31 Dec 1901 · 268 km away

    Limited damage (under $1M)tsunami

  2. 1965M6.5

    Aleutian Islands: Fox Islands

    2 Jul 1965 · 72 km away

    Limited damage (under $1M)tsunami

  3. 1917M7.9

    Alaska Peninsula

    31 May 1917 · 290 km away · intensity V

  4. 1902M7.8

    Aleutian Islands: Fox Islands

    1 Jan 1902 · 6 km away

  5. 1907M7.8

    Aleutian Islands

    2 Sep 1907 · 159 km away

  6. 1929M7.8

    Aleutian Islands: Fox Islands

    7 Mar 1929 · 236 km away · intensity V

    tsunami

NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.

Nearby trackers

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