Reviewed by USGSAlaska2y ago
M3.4 earthquake 130 km S of Unalaska, Alaska
Sunday, August 18, 2024, 10:24:48 UTC · 52.701°N, 166.616°W
A magnitude 3.4 earthquake struck 130 km S of Unalaska, Alaska on Sunday, August 18, 2024, 10:24:48 UTC, at a depth of 6.9 km (shallow).
- Magnitude
- 3.4
- Minor · ml
- Depth
- 7 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
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
39 km
from the nearest mapped plate boundary, between the North American and Pacific plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
7 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 4 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M3.4 on August 31, 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 681 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 · 267 km E of this epicenter
- 7.8234 km SSW of Nikolski, AlaskaMarch 7, 1929 · 296 km SW of this epicenter
- 7.881 km E of Nikolski, AlaskaJuly 2, 1965 · 78 km NW of this epicenter
- 7.4133 km WNW of Nikolski, AlaskaApril 18, 1916 · 283 km W of this epicenter
- 7.139 km S of Akutan, AlaskaMarch 22, 1957 · 132 km NE of this epicenter
- 7.135 km SW of Nikolski, AlaskaMarch 11, 1957 · 174 km W of this epicenter
- 7.0203 km SSE of Unalaska, AlaskaAugust 22, 1940 · 97 km SE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 13 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 · 267 km away · intensity VI
168 deaths$26 million damagetsunami
- 1965M6.5
Aleutian Islands: Fox Islands
2 Jul 1965 · 73 km away
Limited damage (under $1M)tsunami
- 1917M7.9
Alaska Peninsula
31 May 1917 · 285 km away · intensity V
- 1902M7.8
Aleutian Islands: Fox Islands
1 Jan 1902 · 69 km away
- 1907M7.8
Aleutian Islands
2 Sep 1907 · 210 km away
- 1929M7.8
Aleutian Islands: Fox Islands
7 Mar 1929 · 300 km away · intensity V
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.