Reviewed by USGSAlaska87y ago
M6.0 earthquake 175 km SSE of Attu Station, Alaska
Friday, April 19, 1940, 00:06:47 UTC · 51.334°N, 173.888°E
A magnitude 6.0 earthquake struck 175 km SSE of Attu Station, Alaska on Friday, April 19, 1940, 00:06:47 UTC, at a depth of 15.0 km (shallow). It is the strongest earthquake within 300 km since an M7.0 on April 16, 1940.
- Magnitude
- 6.0
- Strong · 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
15 kilotons of TNT
That is about the energy of the Hiroshima bomb. It released about 32 times the energy of a magnitude 5.0.
Tectonic setting
15 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 100 km
USGS has not published any M2.5+ earthquake within 100 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 24 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.993 km NW of Attu Station, AlaskaDecember 17, 1929 · 261 km NW of this epicenter
- 7.4151 km S of Attu Station, AlaskaSeptember 2, 1907 · 77 km W of this epicenter
- 7.2238 km SSE of Attu Station, AlaskaSeptember 8, 1939 · 83 km SE of this epicenter
- 7.024 km E of Attu Station, AlaskaApril 16, 1940 · 170 km N of this epicenter
- 7.080 km SSE of Attu Station, AlaskaApril 16, 1940 · 99 km N of this epicenter
- 7.0167 km WSW of Attu Station, AlaskaApril 10, 1909 · 228 km NW of this epicenter
- 6.8129 km SSE of Attu Station, AlaskaNovember 13, 1911 · 46 km N of this epicenter
- 6.895 km SE of Attu Station, AlaskaFebruary 22, 1935 · 109 km N of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 3 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1909M7.8
Aleutian Islands
10 Apr 1909 · 107 km away
- 1929M7.8
Aleutian Islands: Near Islands
17 Dec 1929 · 209 km away
- 1898M7.6
Aleutian Islands: Near Islands
29 Jun 1898 · 150 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.