Reviewed by USGSAlaska62y ago
M7.8 earthquake 81 km E of Nikolski, Alaska
Friday, July 2, 1965, 20:58:39 UTC · 53.009°N, 167.653°W
A magnitude 7.8 earthquake struck 81 km E of Nikolski, Alaska on Friday, July 2, 1965, 20:58:39 UTC, at a depth of 39.0 km (shallow). It is the strongest earthquake within 300 km since an M7.8 on March 7, 1929.
- Magnitude
- 7.8
- Major · mw
- Depth
- 39 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- VII
- Very strong (ShakeMap)
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeDashed circle: 200 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)
In context
How big was it, and why here?
Energy released
7.6 megatons of TNT
That is about 502 times the Hiroshima bomb. It released about 15,849 times the energy of a magnitude 5.0.
Tectonic setting
97 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
39 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 200 km
USGS lists 1 M2.5+ earthquake within 200 km in the following 30 days; the largest was M5.5 on July 14, 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 155 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.8234 km SSW of Nikolski, AlaskaMarch 7, 1929 · 276 km SW of this epicenter
- 7.4133 km WNW of Nikolski, AlaskaApril 18, 1916 · 206 km W of this epicenter
- 7.139 km S of Akutan, AlaskaMarch 22, 1957 · 151 km NE of this epicenter
- 7.135 km SW of Nikolski, AlaskaMarch 11, 1957 · 109 km W of this epicenter
- 7.0203 km SSE of Unalaska, AlaskaAugust 22, 1940 · 174 km SE of this epicenter
- 6.980 km SW of Nikolski, AlaskaMarch 9, 1957 · 147 km SW of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 12 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 · 287 km away
Limited damage (under $1M)tsunami
- 1965M6.5
Aleutian Islands: Fox Islands
2 Jul 1965 · 7 km away
Limited damage (under $1M)tsunami
- 1917M7.9
Alaska Peninsula
31 May 1917 · 220 km away · intensity V
- 1902M7.8
Aleutian Islands: Fox Islands
1 Jan 1902 · 68 km away
- 1907M7.8
Aleutian Islands
2 Sep 1907 · 147 km away
- 1929M7.8
Aleutian Islands: Fox Islands
7 Mar 1929 · 275 km away · intensity V
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.