Reviewed by USGSAlaska81y ago
M6.8 earthquake 57 km SSW of Atka, Alaska
Friday, November 1, 1946, 11:14:27 UTC · 51.700°N, 174.437°W
A magnitude 6.8 earthquake struck 57 km SSW of Atka, Alaska on Friday, November 1, 1946, 11:14:27 UTC, at a depth of 25.0 km (shallow). It is the strongest earthquake within 300 km since an M7.3 on July 7, 1929.
- Magnitude
- 6.8
- Strong · mw
- Depth
- 25 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- VI
- Strong (ShakeMap)
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeColoured lines: estimated shaking intensity (USGS ShakeMap)
In context
How big was it, and why here?
Energy released
284 kilotons of TNT
That is about 19 times the Hiroshima bomb. It released about 596 times the energy of a magnitude 5.0.
Tectonic setting
91 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 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 76 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.65 km WNW of Adak, AlaskaFebruary 14, 1905 · 157 km W of this epicenter
- 7.388 km WSW of Adak, AlaskaJuly 7, 1929 · 230 km W of this epicenter
- 7.0101 km S of Adak, AlaskaSeptember 9, 1910 · 155 km SW of this epicenter
- 7.0114 km WSW of Adak, AlaskaJuly 5, 1929 · 258 km W of this epicenter
- 6.9182 km SSE of Atka, AlaskaJanuary 27, 1906 · 151 km SE of this epicenter
- 6.9100 km ESE of Adak, AlaskaOctober 13, 1926 · 62 km W of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 2 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1901M7.8
Aleutian Islands: Fox Islands
31 Dec 1901 · 238 km away
Limited damage (under $1M)tsunami
- 1946
East Aleutian Islands
1 Nov 1946 · 23 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.