QuakeScout
Magnitude3.3

Reviewed by USGSAlaska14y ago

M3.3 earthquake 33 km N of Atka, Alaska

Monday, February 6, 2012, 17:08:16 UTC · 52.501°N, 174.221°W

A magnitude 3.3 earthquake struck 33 km N of Atka, Alaska on Monday, February 6, 2012, 17:08:16 UTC, at a depth of 205.3 km (intermediate).

Magnitude
3.3
Minor · ml
Depth
205 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

176 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

205 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 1 M2.5+ earthquake within 50 km in the following 30 days; the largest was M2.7 on February 13, 2012. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

M31h6h1d3d7d14d30dMainshock M3.3
Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.
  1. 2.722 km E of Atka, Alaska14y ago · 41 km SE of this epicenter

Regional history

Past M5+ earthquakes within 300 km

USGS lists 814 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

  1. 8.61957 Atka, Alaska EarthquakeMarch 9, 1957 · 147 km SW of this epicenter
  2. 8.01986 Atka, Alaska EarthquakeMay 7, 1986 · 115 km S of this epicenter
  3. 7.977 km WSW of Adak, AlaskaJune 10, 1996 · 255 km SW of this epicenter
  4. 7.65 km WNW of Adak, AlaskaFebruary 14, 1905 · 182 km W of this epicenter
  5. 7.4133 km WNW of Nikolski, AlaskaApril 18, 1916 · 260 km NE of this epicenter
  6. 7.388 km WSW of Adak, AlaskaJuly 7, 1929 · 267 km SW of this epicenter
  7. 7.346 km SSW of Adak, AlaskaJune 10, 1996 · 213 km SW of this epicenter
  8. 7.3Fox Islands, Aleutian Islands, AlaskaJune 24, 2011 · 170 km E of this epicenter

History · NOAA

Deadliest earthquakes in this area

NOAA’s significant-earthquake database lists 11 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 2 recorded deaths. The most severe:

  1. 1957M8.6

    Alaska

    9 Mar 1957 · 147 km away

    2 deathsSevere damage ($5–24M)tsunami

  2. 1986M8.0

    Aleutian Islands: Adak

    7 May 1986 · 115 km away · intensity VI

    Moderate damage ($1–5M)tsunami

  3. 1901M7.8

    Aleutian Islands: Fox Islands

    31 Dec 1901 · 248 km away

    Limited damage (under $1M)tsunami

  4. 1996M7.9

    Andreanof Islands

    10 Jun 1996 · 255 km away · intensity VI

    tsunami

  5. 1916M7.5

    Aleutian Islands: Fox Islands

    18 Apr 1916 · 297 km away

  6. 1996M7.3

    Andreanof Islands

    10 Jun 1996 · 213 km away

    tsunami

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

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