Reviewed by USGSAlaska2y ago
M3.8 earthquake 42 km S of Sand Point, Alaska
Monday, December 25, 2023, 23:39:41 UTC · 54.954°N, 160.429°W
A magnitude 3.8 earthquake struck 42 km S of Sand Point, Alaska on Monday, December 25, 2023, 23:39:41 UTC, at a depth of 51.5 km (shallow). USGS received 1 “Did You Feel It?” report, with a maximum reported intensity of IV (light).
- Magnitude
- 3.8
- Minor · mb
- Depth
- 52 km
- Shallow
- Felt reports
- 1
- Max intensity IV
- Est. shaking
- II
- Weak (ShakeMap)
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeDashed circle: 50 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)
In context
How big was it, and why here?
Energy released
8 tons of TNT
That is about 1/1,992 of the Hiroshima bomb. A magnitude 5.0 releases about 63 times more energy.
Tectonic setting
135 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
52 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
Reports sent by people to USGS, grouped by place (most reports first). Intensity uses the Modified Mercalli scale (I–X): what people felt, not the magnitude.
| Place | Intensity | Reports | Distance |
|---|---|---|---|
| 99661<br>0.330 | IV · Light | 1 | 64 km |
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 4 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M3.2 on January 17, 2024. 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 397 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 · 225 km SW of this epicenter
- 8.21938 Semidi Islands, Alaska EarthquakeNovember 10, 1938 · 145 km E of this epicenter
- 8.22021 Chignik, Alaska EarthquakeJuly 29, 2021 · 168 km E of this epicenter
- 7.82020 Perryville, Alaska EarthquakeJuly 22, 2020 · 118 km E of this epicenter
- 7.62020 Sand Point, Alaska EarthquakeOctober 19, 2020 · 65 km SE of this epicenter
- 7.454 km SE of Sand Point, AlaskaMay 31, 1917 · 35 km E of this epicenter
- 7.22023 Sand Point, Alaska EarthquakeJuly 16, 2023 · 66 km S of this epicenter
- 7.190 km SE of King Cove, AlaskaMay 14, 1948 · 62 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, which together caused about 169 recorded deaths. The most severe:
- 1946M8.6
Unimak Island
1 Apr 1946 · 225 km away · intensity VI
168 deaths$26 million damagetsunami
- 2023M7.2
Alaska Peninsula
16 Jul 2023 · 59 km away · intensity VI
1 deathtsunami
- 2020M7.8
Alaska
22 Jul 2020 · 118 km away · intensity VII
Limited damage (under $1M)tsunami
- 1938M8.2
Alaska
10 Nov 1938 · 143 km away · intensity VI
tsunami
- 2021M8.2
Alaska Peninsula
29 Jul 2021 · 170 km away · intensity VIII
tsunami
- 1788M8.0
Alaska Peninsula
6 Aug 1788 · 37 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.