Reviewed by USGSAlaska70y ago
M7.1 earthquake 75 km S of Adak, Alaska
Thursday, March 14, 1957, 14:47:50 UTC · 51.196°N, 176.733°W
A magnitude 7.1 earthquake struck 75 km S of Adak, Alaska on Thursday, March 14, 1957, 14:47:50 UTC, at a depth of 25.0 km (shallow). It is the strongest earthquake within 300 km since an M8.6 on March 9, 1957.
- Magnitude
- 7.1
- Major · 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: 200 km aftershock search area
In context
How big was it, and why here?
Energy released
773 kilotons of TNT
That is about 51 times the Hiroshima bomb. It released about 1,622 times the energy of a magnitude 5.0.
Tectonic setting
72 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 200 km
USGS lists 8 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M7.2 on March 16, 1957. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
- 5.8176 km S of Adak, Alaska70y ago · 101 km S of this epicenter
- 5.9Andreanof Islands, Aleutian Islands, Alaska70y ago · 133 km W of this epicenter
- 5.8125 km WSW of Adak, Alaska70y ago · 123 km W of this epicenter
- 6.899 km SW of Atka, Alaska70y ago · 117 km E of this epicenter
- 6.061 km SSW of Adak, Alaska70y ago · 18 km NW of this epicenter
- 6.0Andreanof Islands, Aleutian Islands, Alaska70y ago · 187 km W of this epicenter
- 7.2162 km WSW of Adak, Alaska70y ago · 151 km W of this epicenter
Regional history
Past M5+ earthquakes within 300 km
USGS lists 130 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.61957 Atka, Alaska EarthquakeMarch 9, 1957 · 84 km NE of this epicenter
- 7.65 km WNW of Adak, AlaskaFebruary 14, 1905 · 77 km N of this epicenter
- 7.388 km WSW of Adak, AlaskaJuly 7, 1929 · 77 km NW of this epicenter
- 7.2238 km WSW of Adak, AlaskaMarch 22, 1905 · 218 km W of this epicenter
- 7.160 km SW of Adak, AlaskaMarch 12, 1957 · 48 km NW of this epicenter
- 7.0Rat Islands, Aleutian Islands, AlaskaFebruary 6, 1916 · 300 km W of this epicenter
- 7.0101 km S of Adak, AlaskaSeptember 9, 1910 · 36 km SE of this epicenter
- 7.0114 km WSW of Adak, AlaskaJuly 5, 1929 · 103 km W 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, which together caused about 2 recorded deaths. The most severe:
- 1957M8.6
Alaska
9 Mar 1957 · 84 km away
2 deathsSevere damage ($5–24M)tsunami
- 1905M7.9
Andreanof Islands
14 Feb 1905 · 137 km away
- 1946
East Aleutian Islands
1 Nov 1946 · 159 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.