Reviewed by USGSAlaska70y ago
M6.3 earthquake 143 km E of Atka, Alaska
Friday, April 5, 1957, 02:49:47 UTC · 52.011°N, 172.133°W
A magnitude 6.3 earthquake struck 143 km E of Atka, Alaska on Friday, April 5, 1957, 02:49:47 UTC, at a depth of 35.0 km (shallow). It is the strongest earthquake within 300 km since an M6.8 on March 19, 1957.
- Magnitude
- 6.3
- Strong · mw
- Depth
- 35 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
47 kilotons of TNT
That is about 3 times the Hiroshima bomb. It released about 99 times the energy of a magnitude 5.0.
Tectonic setting
98 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
35 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 101 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 · 247 km W of this epicenter
- 7.8234 km SSW of Nikolski, AlaskaMarch 7, 1929 · 204 km SE of this epicenter
- 7.4133 km WNW of Nikolski, AlaskaApril 18, 1916 · 187 km NE of this epicenter
- 7.135 km SW of Nikolski, AlaskaMarch 11, 1957 · 214 km E of this epicenter
- 6.980 km SW of Nikolski, AlaskaMarch 9, 1957 · 180 km E of this epicenter
- 6.9182 km SSE of Atka, AlaskaJanuary 27, 1906 · 141 km S of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 7 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 · 247 km away
2 deathsSevere damage ($5–24M)tsunami
- 1901M7.8
Aleutian Islands: Fox Islands
31 Dec 1901 · 99 km away
Limited damage (under $1M)tsunami
- 1907M7.8
Aleutian Islands
2 Sep 1907 · 176 km away
- 1929M7.8
Aleutian Islands: Fox Islands
7 Mar 1929 · 186 km away · intensity V
tsunami
- 1916M7.5
Aleutian Islands: Fox Islands
18 Apr 1916 · 203 km away
- 1872
Aleutian Islands: Fox Islands
23 Aug 1872 · 249 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.