QuakeScout
Magnitude2.8

Reviewed by USGSAlaska11y ago

M2.8 earthquake 160 km SW of Nikolski, Alaska

Monday, September 21, 2015, 02:13:20 UTC · 51.827°N, 170.357°W

A magnitude 2.8 earthquake struck 160 km SW of Nikolski, Alaska on Monday, September 21, 2015, 02:13:20 UTC, at a depth of 35.7 km (shallow).

Magnitude
2.8
Minor · ml
Depth
36 km
Shallow
Felt reports
0
Max intensity I
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

239 kg of TNT

That is about 1/63,000 of the Hiroshima bomb. A magnitude 5.0 releases about 1,995 times more energy.

Tectonic setting

45 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

36 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 M3.8 on September 25, 2015. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

M3M41h6h1d3d7d14d30dMainshock M2.8
Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.
  1. 2.7141 km SW of Nikolski, Alaska11y ago · 30 km N of this epicenter
  2. 2.7159 km SW of Nikolski, Alaska11y ago · 46 km NW of this epicenter
  3. 3.8150 km SSW of Nikolski, Alaska11y ago · 33 km E of this epicenter
  4. 2.7Fox Islands, Aleutian Islands, Alaska11y ago · 49 km N of this epicenter
  5. 2.7148 km SW of Nikolski, Alaska11y ago · 41 km NW of this epicenter

Regional history

Past M5+ earthquakes within 300 km

USGS lists 736 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 · 110 km S of this epicenter
  2. 7.881 km E of Nikolski, AlaskaJuly 2, 1965 · 226 km NE of this epicenter
  3. 7.4133 km WNW of Nikolski, AlaskaApril 18, 1916 · 181 km N of this epicenter
  4. 7.3Fox Islands, Aleutian Islands, AlaskaJune 24, 2011 · 104 km W of this epicenter
  5. 7.135 km SW of Nikolski, AlaskaMarch 11, 1957 · 125 km NE of this epicenter
  6. 6.980 km SW of Nikolski, AlaskaMarch 9, 1957 · 80 km NE 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:

  1. 1901M7.8

    Aleutian Islands: Fox Islands

    31 Dec 1901 · 62 km away

    Limited damage (under $1M)tsunami

  2. 1965M6.5

    Aleutian Islands: Fox Islands

    2 Jul 1965 · 233 km away

    Limited damage (under $1M)tsunami

  3. 1902M7.8

    Aleutian Islands: Fox Islands

    1 Jan 1902 · 205 km away

  4. 1907M7.8

    Aleutian Islands

    2 Sep 1907 · 95 km away

  5. 1929M7.8

    Aleutian Islands: Fox Islands

    7 Mar 1929 · 95 km away · intensity V

    tsunami

  6. 1916M7.5

    Aleutian Islands: Fox Islands

    18 Apr 1916 · 166 km away

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

Nearby trackers

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