Reviewed by USGSAlaska62y ago
M5.5 earthquake in Rat Islands, Aleutian Islands, Alaska
Wednesday, March 31, 1965, 10:46:08 UTC · 50.200°N, 178.388°E
A magnitude 5.5 earthquake struck in Rat Islands, Aleutian Islands, Alaska on Wednesday, March 31, 1965, 10:46:08 UTC, at a depth of 15.0 km (shallow). It is the strongest earthquake within 300 km since an M7.6 on March 30, 1965.
- Magnitude
- 5.5
- 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
3 kilotons of TNT
That is about 1/5 of the Hiroshima bomb. It released about 7 times the energy of a magnitude 5.0.
Tectonic setting
47 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 155 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.71965 Western Aleutian Islands (Hawadax/Rat Islands) EarthquakeFebruary 4, 1965 · 119 km N of this epicenter
- 8.31906 Western Aleutian Islands (Hawadax/Rat Islands) EarthquakeAugust 17, 1906 · 184 km N of this epicenter
- 7.6Rat Islands, Aleutian Islands, AlaskaMarch 30, 1965 · 38 km W of this epicenter
- 7.4265 km WSW of Adak, AlaskaFebruary 4, 1965 · 161 km NE of this epicenter
- 7.2238 km SSE of Attu Station, AlaskaSeptember 8, 1939 · 258 km W of this epicenter
- 7.2238 km WSW of Adak, AlaskaMarch 22, 1905 · 162 km NE of this epicenter
- 7.2162 km WSW of Adak, AlaskaMarch 16, 1957 · 236 km NE of this epicenter
- 7.0Rat Islands, Aleutian Islands, AlaskaFebruary 6, 1916 · 79 km NE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 6 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1965M8.7
Aleutian Islands: Rat Islands
4 Feb 1965 · 119 km away · intensity VI
Under $1 million damagetsunami
- 1906M8.3
Aleutian Islands: Rat Islands
17 Aug 1906 · 184 km away
- 1905M7.9
Andreanof Islands
14 Feb 1905 · 225 km away
- 1916M7.7
Aleutian Islands
6 Feb 1916 · 189 km away
- 1965M7.6
Aleutian Islands: Rat Islands
30 Mar 1965 · 35 km away
tsunami
- 1940M7.4
Aleutian Islands: Rat Islands
14 Jul 1940 · 201 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.