QuakeScout
Magnitude2.7

Reviewed by USGSAlaska5y ago

M2.7 earthquake 57 km ENE of Chignik, Alaska

Thursday, March 4, 2021, 00:55:07 UTC · 56.486°N, 157.541°W

A magnitude 2.7 earthquake struck 57 km ENE of Chignik, Alaska on Thursday, March 4, 2021, 00:55:07 UTC, at a depth of 66.3 km (shallow).

Magnitude
2.7
Minor · ml
Depth
66 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

169 kg of TNT

That is about 1/88,990 of the Hiroshima bomb. A magnitude 5.0 releases about 2,818 times more energy.

Tectonic setting

232 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

66 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 March 27, 2021. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

M31h6h1d3d7d14d30dMainshock M2.7
Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.
  1. 2.630 km NE of Chignik, Alaska5y ago · 36 km W of this epicenter
  2. 2.823 km ESE of Chignik, Alaska5y ago · 47 km SW of this epicenter

Regional history

Past M5+ earthquakes within 300 km

USGS lists 375 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 · 151 km S of this epicenter
  2. 7.82020 Perryville, Alaska EarthquakeJuly 22, 2020 · 171 km SW of this epicenter
  3. 7.62020 Sand Point, Alaska EarthquakeOctober 19, 2020 · 247 km SW of this epicenter
  4. 7.454 km SE of Sand Point, AlaskaMay 31, 1917 · 221 km SW of this epicenter
  5. 7.14 km ENE of Karluk, AlaskaNovember 7, 1912 · 227 km NE of this epicenter
  6. 7.0113 km ESE of Chignik, AlaskaMay 4, 1923 · 86 km SE of this epicenter
  7. 7.026 km SSE of Karluk, AlaskaDecember 6, 1999 · 216 km NE 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. 1900M8.3

    Kodiak Island

    9 Oct 1900 · 256 km away · intensity VIII

    Limited damage (under $1M)

  2. 1788M8.0

    Unga Island

    21 Jul 1788 · 283 km away · intensity VII

    Limited damage (under $1M)tsunami

  3. 2020M7.8

    Alaska

    22 Jul 2020 · 171 km away · intensity VII

    Limited damage (under $1M)tsunami

  4. 1970M6.0

    Andreanof Islands

    11 Mar 1970 · 248 km away · intensity V

    Limited damage (under $1M)tsunami

  5. 1938M8.2

    Alaska

    10 Nov 1938 · 123 km away · intensity VI

    tsunami

  6. 2021M8.2

    Alaska Peninsula

    29 Jul 2021 · 131 km away · intensity VIII

    tsunami

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

Nearby trackers

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