Reviewed by USGSAlaska3y ago
M2.9 earthquake 40 km SSE of False Pass, Alaska
Tuesday, August 29, 2023, 16:17:19 UTC · 54.501°N, 163.255°W
A magnitude 2.9 earthquake struck 40 km SSE of False Pass, Alaska on Tuesday, August 29, 2023, 16:17:19 UTC, at a depth of 10.0 km (shallow).
- Magnitude
- 2.9
- Minor · ml
- Depth
- 10 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
136 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
10 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 5 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M3.2 on September 9, 2023. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
- 2.839 km S of False Pass, Alaska3y ago · 7 km W of this epicenter
- 2.585 km S of False Pass, Alaska3y ago · 48 km S of this epicenter
- 2.748 km S of False Pass, Alaska3y ago · 9 km S of this epicenter
- 3.239 km SW of False Pass, Alaska3y ago · 36 km W of this epicenter
- 2.650 km SSW of False Pass, Alaska3y ago · 35 km W of this epicenter
Regional history
Past M5+ earthquakes within 300 km
USGS lists 412 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.6The 1946 Unimak Island, Alaska EarthquakeApril 1, 1946 · 116 km S of this epicenter
- 7.62020 Sand Point, Alaska EarthquakeOctober 19, 2020 · 234 km E of this epicenter
- 7.454 km SE of Sand Point, AlaskaMay 31, 1917 · 223 km E of this epicenter
- 7.22023 Sand Point, Alaska EarthquakeJuly 16, 2023 · 162 km E of this epicenter
- 7.190 km SE of King Cove, AlaskaMay 14, 1948 · 135 km E of this epicenter
- 7.139 km S of Akutan, AlaskaMarch 22, 1957 · 183 km SW of this epicenter
- 7.071 km SE of King Cove, AlaskaMay 30, 1991 · 107 km E of this epicenter
- 7.0203 km SSE of Unalaska, AlaskaAugust 22, 1940 · 300 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, which together caused about 169 recorded deaths. The most severe:
- 1946M8.6
Unimak Island
1 Apr 1946 · 116 km away · intensity VI
168 deaths$26 million damagetsunami
- 2023M7.2
Alaska Peninsula
16 Jul 2023 · 161 km away · intensity VI
1 deathtsunami
- 1788M8.0
Alaska Peninsula
6 Aug 1788 · 155 km away
tsunami
- 2020M7.6
Alaska
19 Oct 2020 · 234 km away · intensity IX
tsunami
- 1948M7.5
Alaska Peninsula
14 May 1948 · 146 km away
- 1957M7.5
Aleutian Islands: Fox Islands
22 Mar 1957 · 137 km away · intensity V
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.