Reviewed by USGSAlaska2y ago
M3.4 earthquake 15 km ENE of Unalaska, Alaska
Sunday, September 1, 2024, 17:31:45 UTC · 53.909°N, 166.302°W
A magnitude 3.4 earthquake struck 15 km ENE of Unalaska, Alaska on Sunday, September 1, 2024, 17:31:45 UTC, at a depth of 11.7 km (shallow). USGS received 2 “Did You Feel It?” reports, with a maximum reported intensity of III (weak).
- Magnitude
- 3.4
- Minor · ml
- Depth
- 12 km
- Shallow
- Felt reports
- 2
- Max intensity III
- 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
2 tons of TNT
That is about 1/7,931 of the Hiroshima bomb. A magnitude 5.0 releases about 251 times more energy.
Tectonic setting
153 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
12 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 |
|---|---|---|---|
| 99685<br>0.320 | III · Weak | 2 | 27 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 2 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M3.7 on September 22, 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 615 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 · 233 km E of this epicenter
- 7.881 km E of Nikolski, AlaskaJuly 2, 1965 · 134 km SW of this epicenter
- 7.4133 km WNW of Nikolski, AlaskaApril 18, 1916 · 292 km W of this epicenter
- 7.139 km S of Akutan, AlaskaMarch 22, 1957 · 38 km SE of this epicenter
- 7.135 km SW of Nikolski, AlaskaMarch 11, 1957 · 235 km SW of this epicenter
- 7.0203 km SSE of Unalaska, AlaskaAugust 22, 1940 · 202 km S of this epicenter
- 6.980 km SW of Nikolski, AlaskaMarch 9, 1957 · 277 km SW of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 12 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 168 recorded deaths. The most severe:
- 1946M8.6
Unimak Island
1 Apr 1946 · 233 km away · intensity VI
168 deaths$26 million damagetsunami
- 1965M6.5
Aleutian Islands: Fox Islands
2 Jul 1965 · 128 km away
Limited damage (under $1M)tsunami
- 1917M7.9
Alaska Peninsula
31 May 1917 · 207 km away · intensity V
- 1902M7.8
Aleutian Islands: Fox Islands
1 Jan 1902 · 186 km away
- 1907M7.8
Aleutian Islands
2 Sep 1907 · 271 km away
- 1916M7.5
Aleutian Islands: Fox Islands
18 Apr 1916 · 253 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.