QuakeScout
Magnitude3.8

Reviewed by USGSAlaska11y ago

M3.8 earthquake in Rat Islands, Aleutian Islands, Alaska

Tuesday, March 31, 2015, 23:39:52 UTC · 51.060°N, 179.158°E

A magnitude 3.8 earthquake struck in Rat Islands, Aleutian Islands, Alaska on Tuesday, March 31, 2015, 23:39:52 UTC, at a depth of 30.2 km (shallow).

Magnitude
3.8
Minor · mb
Depth
30 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

8 tons of TNT

That is about 1/1,992 of the Hiroshima bomb. A magnitude 5.0 releases about 63 times more energy.

Tectonic setting

55 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

30 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 3 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M2.7 on April 14, 2015. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

M3M41h6h1d3d7d14d30dMainshock M3.8
Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.
  1. 2.7270 km WSW of Adak, Alaska11y ago · 42 km NE of this epicenter
  2. 2.5282 km WSW of Adak, Alaska11y ago · 27 km E of this epicenter
  3. 2.5Rat Islands, Aleutian Islands, Alaska11y ago · 10 km SE of this epicenter

Regional history

Past M5+ earthquakes within 300 km

USGS lists 953 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 · 38 km NW of this epicenter
  2. 8.31906 Western Aleutian Islands (Hawadax/Rat Islands) EarthquakeAugust 17, 1906 · 111 km NW of this epicenter
  3. 7.977 km WSW of Adak, AlaskaJune 10, 1996 · 230 km E of this epicenter
  4. 7.9Rat Islands, Aleutian Islands, AlaskaJune 23, 2014 · 92 km N of this epicenter
  5. 7.8Rat Islands, Aleutian Islands, AlaskaNovember 17, 2003 · 37 km W of this epicenter
  6. 7.6Rat Islands, Aleutian Islands, AlaskaMarch 30, 1965 · 125 km SW of this epicenter
  7. 7.4265 km WSW of Adak, AlaskaFebruary 4, 1965 · 52 km NE of this epicenter
  8. 7.388 km WSW of Adak, AlaskaJuly 7, 1929 · 220 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:

  1. 1965M8.7

    Aleutian Islands: Rat Islands

    4 Feb 1965 · 38 km away · intensity VI

    Under $1 million damagetsunami

  2. 1906M8.3

    Aleutian Islands: Rat Islands

    17 Aug 1906 · 111 km away

  3. 1905M7.9

    Andreanof Islands

    14 Feb 1905 · 165 km away

  4. 1996M7.9

    Andreanof Islands

    10 Jun 1996 · 230 km away · intensity VI

    tsunami

  5. 2014M7.9

    Aleutian Islands

    23 Jun 2014 · 93 km away · intensity VI

    tsunami

  6. 2003M7.8

    Aleutian Islands: Rat Islands

    17 Nov 2003 · 37 km away

    tsunami

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

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