QuakeScout
Magnitude2.6

Reviewed by USGSAlaska5y ago

M2.6 earthquake 70 km SSE of Chignik, Alaska

Sunday, April 11, 2021, 06:54:08 UTC · 55.732°N, 157.889°W

A magnitude 2.6 earthquake struck 70 km SSE of Chignik, Alaska on Sunday, April 11, 2021, 06:54:08 UTC, at a depth of 35.7 km (shallow).

Magnitude
2.6
Minor · ml
Depth
36 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

120 kg of TNT

That is about 1/125,702 of the Hiroshima bomb. A magnitude 5.0 releases about 3,981 times more energy.

Tectonic setting

164 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: 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 2 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M2.6 on April 14, 2021. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

1h6h1d3d7d14d30dMainshock M2.6
Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.
  1. 2.679 km SE of Perryville, Alaska5y ago · 45 km SW of this epicenter
  2. 2.561 km ESE of Chignik, Alaska5y ago · 44 km NE of this epicenter

Regional history

Past M5+ earthquakes within 300 km

USGS lists 340 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

  1. 8.21938 Semidi Islands, Alaska EarthquakeNovember 10, 1938 · 64 km S of this epicenter
  2. 7.82020 Perryville, Alaska EarthquakeJuly 22, 2020 · 86 km SW of this epicenter
  3. 7.62020 Sand Point, Alaska EarthquakeOctober 19, 2020 · 167 km SW of this epicenter
  4. 7.454 km SE of Sand Point, AlaskaMay 31, 1917 · 150 km SW of this epicenter
  5. 7.190 km SE of King Cove, AlaskaMay 14, 1948 · 243 km SW of this epicenter
  6. 7.14 km ENE of Karluk, AlaskaNovember 7, 1912 · 297 km NE of this epicenter
  7. 7.0113 km ESE of Chignik, AlaskaMay 4, 1923 · 71 km E of this epicenter
  8. 7.071 km SE of King Cove, AlaskaMay 30, 1991 · 269 km SW 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. The most severe:

  1. 2020M7.8

    Alaska

    22 Jul 2020 · 86 km away · intensity VII

    Limited damage (under $1M)tsunami

  2. 1938M8.2

    Alaska

    10 Nov 1938 · 41 km away · intensity VI

    tsunami

  3. 2021M8.2

    Alaska Peninsula

    29 Jul 2021 · 45 km away · intensity VIII

    tsunami

  4. 1788M8.0

    Alaska Peninsula

    6 Aug 1788 · 213 km away

    tsunami

  5. 1906M7.6

    Aleutian Islands

    23 Dec 1906 · 276 km away

  6. 2020M7.6

    Alaska

    19 Oct 2020 · 167 km away · intensity IX

    tsunami

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

Nearby trackers

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