Reviewed by USGSAlaska81y ago
M6.2 earthquake 172 km SSE of False Pass, Alaska
Tuesday, April 2, 1946, 05:57:13 UTC · 53.340°N, 162.850°W
A magnitude 6.2 earthquake struck 172 km SSE of False Pass, Alaska on Tuesday, April 2, 1946, 05:57:13 UTC, at a depth of 25.0 km (shallow). It is the strongest earthquake within 300 km since an M6.2 on April 2, 1946.
- Magnitude
- 6.2
- Strong · mw
- Depth
- 25 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: 100 km aftershock search area
In context
How big was it, and why here?
Energy released
30 kilotons of TNT
That is about 2 times the Hiroshima bomb. It released about 63 times the energy of a magnitude 5.0.
Tectonic setting
8 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
25 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 lists 3 M2.5+ earthquakes within 100 km in the following 30 days; the largest was M6.2 on April 6, 1946. 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 41 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 · 17 km N of this epicenter
- 7.454 km SE of Sand Point, AlaskaMay 31, 1917 · 267 km NE of this epicenter
- 7.0203 km SSE of Unalaska, AlaskaAugust 22, 1940 · 222 km SW of this epicenter
- 6.873 km SW of Sand Point, AlaskaJuly 2, 1922 · 197 km NE of this epicenter
- 6.768 km SSE of King Cove, AlaskaApril 29, 1937 · 148 km NE of this epicenter
- 6.6291 km S of Sand Point, AlaskaMay 13, 1910 · 217 km E of this epicenter
- 6.672 km SE of Sand Point, AlaskaOctober 16, 1932 · 276 km NE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 5 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 · 17 km away · intensity VI
168 deaths$26 million damagetsunami
- 1788M8.0
Alaska Peninsula
6 Aug 1788 · 220 km away
tsunami
- 1820
East Aleutian Islands
1 Mar 1820 · 176 km away
tsunami
- 1868
Alaska Peninsula
15 May 1868 · 220 km away
tsunami
- 1878
East Aleutian Islands
29 Aug 1878 · 237 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.