QuakeScout
Magnitude2.8

Reviewed by USGSAlaska11y ago

M2.8 earthquake in Rat Islands, Aleutian Islands, Alaska

Saturday, October 17, 2015, 02:10:38 UTC · 51.629°N, 177.327°E

A magnitude 2.8 earthquake struck in Rat Islands, Aleutian Islands, Alaska on Saturday, October 17, 2015, 02:10:38 UTC, at a depth of 26.3 km (shallow).

Magnitude
2.8
Minor · ml
Depth
26 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

90 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 1 M2.5+ earthquake within 50 km in the following 30 days; the largest was M3.2 on November 14, 2015. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

M31h6h1d3d7d14d30dMainshock M2.8
Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.
  1. 3.2Rat Islands, Aleutian Islands, Alaska11y ago · 21 km S of this epicenter

Regional history

Past M5+ earthquakes within 300 km

USGS lists 805 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

  1. 8.71965 Western Aleutian Islands (Hawadax/Rat Islands) EarthquakeFebruary 4, 1965 · 105 km SE of this epicenter
  2. 8.31906 Western Aleutian Islands (Hawadax/Rat Islands) EarthquakeAugust 17, 1906 · 64 km NE of this epicenter
  3. 7.9Rat Islands, Aleutian Islands, AlaskaJune 23, 2014 · 100 km E of this epicenter
  4. 7.8Rat Islands, Aleutian Islands, AlaskaNovember 17, 2003 · 106 km SE of this epicenter
  5. 7.6Rat Islands, Aleutian Islands, AlaskaMarch 30, 1965 · 154 km S of this epicenter
  6. 7.4265 km WSW of Adak, AlaskaFebruary 4, 1965 · 158 km E of this epicenter
  7. 7.2238 km SSE of Attu Station, AlaskaSeptember 8, 1939 · 179 km W of this epicenter
  8. 7.2207 km WSW of Adak, AlaskaDecember 19, 2007 · 221 km E of this epicenter

History · NOAA

Deadliest earthquakes in this area

NOAA’s significant-earthquake database lists 9 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:

  1. 1965M8.7

    Aleutian Islands: Rat Islands

    4 Feb 1965 · 105 km away · intensity VI

    Under $1 million damagetsunami

  2. 1906M8.3

    Aleutian Islands: Rat Islands

    17 Aug 1906 · 64 km away

  3. 2014M7.9

    Aleutian Islands

    23 Jun 2014 · 100 km away · intensity VI

    tsunami

  4. 1909M7.8

    Aleutian Islands

    10 Apr 1909 · 165 km away

  5. 2003M7.8

    Aleutian Islands: Rat Islands

    17 Nov 2003 · 106 km away

    tsunami

  6. 1965M7.6

    Aleutian Islands: Rat Islands

    30 Mar 1965 · 152 km away

    tsunami

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

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