Reviewed by USGSAlaska5y ago
M2.9 earthquake 34 km S of Ivanof Bay, Alaska
Sunday, August 1, 2021, 05:56:45 UTC · 55.596°N, 159.576°W
A magnitude 2.9 earthquake struck 34 km S of Ivanof Bay, Alaska on Sunday, August 1, 2021, 05:56:45 UTC, at a depth of 61.4 km (shallow).
- Magnitude
- 2.9
- Minor · ml
- Depth
- 61 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
338 kg of TNT
That is about 1/44,601 of the Hiroshima bomb. A magnitude 5.0 releases about 1,413 times more energy.
Tectonic setting
188 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
61 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 3 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M2.6 on August 17, 2021. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 294 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.21938 Semidi Islands, Alaska EarthquakeNovember 10, 1938 · 100 km SE of this epicenter
- 8.22021 Chignik, Alaska EarthquakeJuly 29, 2021 · 109 km E of this epicenter
- 7.82020 Perryville, Alaska EarthquakeJuly 22, 2020 · 85 km SE of this epicenter
- 7.62020 Sand Point, Alaska EarthquakeOctober 19, 2020 · 111 km S of this epicenter
- 7.454 km SE of Sand Point, AlaskaMay 31, 1917 · 70 km S of this epicenter
- 7.190 km SE of King Cove, AlaskaMay 14, 1948 · 150 km SW of this epicenter
- 7.0113 km ESE of Chignik, AlaskaMay 4, 1923 · 178 km E of this epicenter
- 7.071 km SE of King Cove, AlaskaMay 30, 1991 · 173 km SW of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 9 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 2020M7.8
Alaska
22 Jul 2020 · 85 km away · intensity VII
Limited damage (under $1M)tsunami
- 1938M8.2
Alaska
10 Nov 1938 · 77 km away · intensity VI
tsunami
- 2021M8.2
Alaska Peninsula
29 Jul 2021 · 113 km away · intensity VIII
tsunami
- 1788M8.0
Alaska Peninsula
6 Aug 1788 · 112 km away
tsunami
- 2020M7.6
Alaska
19 Oct 2020 · 111 km away · intensity IX
tsunami
- 1948M7.5
Alaska Peninsula
14 May 1948 · 152 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.