Reviewed by USGSAlaska62y ago
M6.2 earthquake 98 km S of Attu Station, Alaska
Thursday, February 25, 1965, 05:22:14 UTC · 51.971°N, 172.997°E
A magnitude 6.2 earthquake struck 98 km S of Attu Station, Alaska on Thursday, February 25, 1965, 05:22:14 UTC, at a depth of 26.9 km (shallow). It is the strongest earthquake within 300 km since an M6.4 on February 4, 1965.
- Magnitude
- 6.2
- Strong · mw
- Depth
- 27 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
33 kilotons of TNT
That is about 2 times the Hiroshima bomb. It released about 70 times the energy of a magnitude 5.0.
Tectonic setting
30 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
27 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 M5.7 on March 1, 1965. 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 102 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 · 172 km N of this epicenter
- 7.4151 km S of Attu Station, AlaskaSeptember 2, 1907 · 53 km S of this epicenter
- 7.2238 km SSE of Attu Station, AlaskaSeptember 8, 1939 · 174 km SE of this epicenter
- 7.024 km E of Attu Station, AlaskaApril 16, 1940 · 105 km N of this epicenter
- 7.080 km SSE of Attu Station, AlaskaApril 16, 1940 · 60 km NE of this epicenter
- 7.0167 km WSW of Attu Station, AlaskaApril 10, 1909 · 145 km W of this epicenter
- 7.0171 km WNW of Attu Station, AlaskaJanuary 5, 1953 · 229 km NW of this epicenter
- 6.8129 km SSE of Attu Station, AlaskaNovember 13, 1911 · 58 km SE 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 · 137 km away
- 1929M7.8
Aleutian Islands: Near Islands
17 Dec 1929 · 118 km away
- 1898M7.6
Aleutian Islands: Near Islands
29 Jun 1898 · 68 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.