M 8.2 earthquake – 2021 Chignik, Alaska Earthquake
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Local time: Jul 28, 2021 · 22:15 (UTC-8)
GreatShallow · 35 kmPAGER yellowTsunami information issued
Reviewed by a seismologist
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- Magnitude
- 8.2moment magnitude (mww)
- Depth
- 35 kmShallow earthquake
- Epicenter
- 55.364, -157.888801 km from Anchorage
- Energy released
- 30 megatons of TNTabout 2,006 × Hiroshima
- Felt reports
- 512"Did You Feel It?" responses
- Shaking intensity
- 7.4max. instrumental (MMI)
- Aftershocks
- 500M2.5+ within 375 km, up to 60 days
- Significance
- 1,500USGS score, 0–1,000+
The strongest here since 1938
The last earthquake at least as strong within 300 km struck on Nov 10, 1938.
How strong was it?
Great earthquake. It released 30 megatons of TNT, 63,096 times the energy of a magnitude 5.0. Bars use the magnitude scale: every step is about 32 times more energy.
Aftershocks
500 earthquakes of M2.5+ within 375 km in the 60 days after.
- 5.5 106 km SSE of Perryville, Alaska Jul 29, 2021
- 5.1 114 km SE of Perryville, Alaska Jul 29, 2021
- 5.7 99 km ESE of Chignik, Alaska Jul 29, 2021
- 5.9 127 km SE of Chignik, Alaska Jul 29, 2021
- 4.2 159 km SE of Chignik, Alaska Jul 29, 2021
- 4.5 106 km SSE of Chignik, Alaska Jul 29, 2021
- 5.3 128 km SE of Perryville, Alaska Jul 29, 2021
- 3.9 118 km SE of Perryville, Alaska Jul 29, 2021
- 5.4 154 km SE of Chignik, Alaska Jul 29, 2021
- 4.2 91 km SSE of Chignik, Alaska Jul 29, 2021
The strongest earthquakes within 300 km
Since 1900.
- 8.2 1938 Semidi Islands, Alaska Earthquake Nov 10, 1938
- 7.8 2020 Perryville, Alaska Earthquake Jul 22, 2020
- 7.6 2020 Sand Point, Alaska Earthquake Oct 19, 2020
- 7.4 54 km SE of Sand Point, Alaska May 31, 1917
- 7.3 2025 Sand Point, Alaska Earthquake Jul 16, 2025
- 7.2 2023 Sand Point, Alaska Earthquake Jul 16, 2023
- 7.1 90 km SE of King Cove, Alaska May 14, 1948
- 7.0 71 km SE of King Cove, Alaska May 30, 1991
In the week before
Earthquakes within 375 km in the 7 days before this one: possible foreshocks.
- 2.7 158 km SSE of False Pass, Alaska Jul 22, 2021
- 2.5 100 km S of False Pass, Alaska Jul 24, 2021
- 2.5 73 km SSE of False Pass, Alaska Jul 25, 2021
- 3.7 57 km WSW of Akhiok, Alaska Jul 27, 2021
- 2.8 81 km SE of King Cove, Alaska Jul 27, 2021
- 3.0 67 km ENE of Ugashik, Alaska Jul 27, 2021
- 3.1 32 km NNE of Cold Bay, Alaska Jul 29, 2021