Reviewed by USGSAlaska88y ago
M5.7 earthquake 230 km SE of Attu Station, Alaska
Friday, September 15, 1939, 21:49:01 UTC · 51.153°N, 175.124°E
A magnitude 5.7 earthquake struck 230 km SE of Attu Station, Alaska on Friday, September 15, 1939, 21:49:01 UTC, at a depth of 15.0 km (shallow). It is the strongest earthquake within 300 km since an M7.2 on September 8, 1939.
- Magnitude
- 5.7
- Moderate · mw
- Depth
- 15 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 earthquake
In context
How big was it, and why here?
Energy released
5 kilotons of TNT
That is about 1/3 of the Hiroshima bomb. It released about 11 times the energy of a magnitude 5.0.
Tectonic setting
6 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
15 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 75 km
USGS has not published any M2.5+ earthquake within 75 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 20 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.31906 Western Aleutian Islands (Hawadax/Rat Islands) EarthquakeAugust 17, 1906 · 225 km E of this epicenter
- 7.4151 km S of Attu Station, AlaskaSeptember 2, 1907 · 165 km W of this epicenter
- 7.2238 km SSE of Attu Station, AlaskaSeptember 8, 1939 · 21 km SW of this epicenter
- 7.0Rat Islands, Aleutian Islands, AlaskaFebruary 6, 1916 · 277 km E of this epicenter
- 6.8129 km SSE of Attu Station, AlaskaNovember 13, 1911 · 115 km NW of this epicenter
- 6.895 km SE of Attu Station, AlaskaFebruary 22, 1935 · 140 km NW of this epicenter
- 6.78 km SE of Attu Station, AlaskaOctober 18, 1912 · 222 km NW of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 4 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1906M8.3
Aleutian Islands: Rat Islands
17 Aug 1906 · 225 km away
- 1909M7.8
Aleutian Islands
10 Apr 1909 · 95 km away
- 1929M7.8
Aleutian Islands: Near Islands
17 Dec 1929 · 291 km away
- 1898M7.6
Aleutian Islands: Near Islands
29 Jun 1898 · 236 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.