QuakeScout
Magnitude2.5

Reviewed by USGSAlaska2y ago

M2.5 earthquake 110 km SSW of Unalaska, Alaska

Tuesday, May 21, 2024, 23:22:09 UTC · 52.938°N, 167.076°W

A magnitude 2.5 earthquake struck 110 km SSW of Unalaska, Alaska on Tuesday, May 21, 2024, 23:22:09 UTC, at a depth of 35.0 km (shallow).

Magnitude
2.5
Minor · ml
Depth
35 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

75 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

35 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 2 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M2.8 on June 2, 2024. 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. 2.8106 km S of Unalaska, Alaska2y ago · 17 km E of this epicenter
  2. 2.8125 km ESE of Nikolski, Alaska2y ago · 49 km S of this epicenter

Regional history

Past M5+ earthquakes within 300 km

USGS lists 703 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

  1. 8.6The 1946 Unimak Island, Alaska EarthquakeApril 1, 1946 · 289 km E of this epicenter
  2. 7.8234 km SSW of Nikolski, AlaskaMarch 7, 1929 · 293 km SW of this epicenter
  3. 7.881 km E of Nikolski, AlaskaJuly 2, 1965 · 39 km W of this epicenter
  4. 7.4133 km WNW of Nikolski, AlaskaApril 18, 1916 · 246 km W of this epicenter
  5. 7.139 km S of Akutan, AlaskaMarch 22, 1957 · 127 km NE of this epicenter
  6. 7.135 km SW of Nikolski, AlaskaMarch 11, 1957 · 145 km W of this epicenter
  7. 7.0203 km SSE of Unalaska, AlaskaAugust 22, 1940 · 137 km SE 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, which together caused about 168 recorded deaths. The most severe:

  1. 1946M8.6

    Unimak Island

    1 Apr 1946 · 289 km away · intensity VI

    168 deaths$26 million damagetsunami

  2. 1965M6.5

    Aleutian Islands: Fox Islands

    2 Jul 1965 · 33 km away

    Limited damage (under $1M)tsunami

  3. 1917M7.9

    Alaska Peninsula

    31 May 1917 · 246 km away · intensity V

  4. 1902M7.8

    Aleutian Islands: Fox Islands

    1 Jan 1902 · 66 km away

  5. 1907M7.8

    Aleutian Islands

    2 Sep 1907 · 183 km away

  6. 1929M7.8

    Aleutian Islands: Fox Islands

    7 Mar 1929 · 294 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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