Reviewed by USGSAlaska10y ago
M3.9 earthquake 90 km SE of Atka, Alaska
Thursday, March 24, 2016, 20:15:35 UTC · 51.603°N, 173.295°W
A magnitude 3.9 earthquake struck 90 km SE of Atka, Alaska on Thursday, March 24, 2016, 20:15:35 UTC, at a depth of 10.0 km (shallow).
- Magnitude
- 3.9
- Minor · mb
- Depth
- 10 km
- Shallow
- Felt reports
- 0
- Max intensity I
- Est. shaking
- —
- No ShakeMap
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeDashed circle: 50 km aftershock search area
In context
How big was it, and why here?
Energy released
11 tons of TNT
That is about 1/1,410 of the Hiroshima bomb. A magnitude 5.0 releases about 45 times more energy.
Tectonic setting
69 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
10 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 50 km
USGS lists 2 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M4.4 on March 25, 2016. 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 925 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 · 162 km W of this epicenter
- 8.01986 Atka, Alaska EarthquakeMay 7, 1986 · 103 km W of this epicenter
- 7.977 km WSW of Adak, AlaskaJune 10, 1996 · 300 km W of this epicenter
- 7.8234 km SSW of Nikolski, AlaskaMarch 7, 1929 · 256 km E of this epicenter
- 7.65 km WNW of Adak, AlaskaFebruary 14, 1905 · 237 km W of this epicenter
- 7.4133 km WNW of Nikolski, AlaskaApril 18, 1916 · 271 km NE of this epicenter
- 7.346 km SSW of Adak, AlaskaJune 10, 1996 · 246 km W of this epicenter
- 7.3Fox Islands, Aleutian Islands, AlaskaJune 24, 2011 · 112 km NE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 14 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 · 162 km away
2 deathsSevere damage ($5–24M)tsunami
- 1986M8.0
Aleutian Islands: Adak
7 May 1986 · 103 km away · intensity VI
Moderate damage ($1–5M)tsunami
- 1901M7.8
Aleutian Islands: Fox Islands
31 Dec 1901 · 158 km away
Limited damage (under $1M)tsunami
- 1996M7.9
Andreanof Islands
10 Jun 1996 · 300 km away · intensity VI
tsunami
- 1907M7.8
Aleutian Islands
2 Sep 1907 · 267 km away
- 1929M7.8
Aleutian Islands: Fox Islands
7 Mar 1929 · 239 km away · intensity V
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.