Reviewed by USGSAlaska10y ago
M4.0 earthquake 23 km W of Atka, Alaska
Tuesday, January 12, 2016, 11:41:21 UTC · 52.220°N, 174.544°W
A magnitude 4.0 earthquake struck 23 km W of Atka, Alaska on Tuesday, January 12, 2016, 11:41:21 UTC, at a depth of 200.5 km (intermediate).
- Magnitude
- 4.0
- Light · mb
- Depth
- 201 km
- Intermediate
- 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
15 tons of TNT
That is about 1/998 of the Hiroshima bomb. A magnitude 5.0 releases about 32 times more energy.
Tectonic setting
149 km
from the nearest mapped plate boundary, between the North American and Pacific plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.
Depth: intermediate
201 km
Intermediate-depth earthquakes usually break inside a plate that is sinking into the mantle. Shaking spreads over a wide area but is gentler at the epicenter than a shallow quake of the same size.
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 3 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M2.8 on January 14, 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 1,006 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 · 109 km SW of this epicenter
- 8.01986 Atka, Alaska EarthquakeMay 7, 1986 · 79 km S of this epicenter
- 7.977 km WSW of Adak, AlaskaJune 10, 1996 · 224 km W of this epicenter
- 7.65 km WNW of Adak, AlaskaFebruary 14, 1905 · 152 km W of this epicenter
- 7.4133 km WNW of Nikolski, AlaskaApril 18, 1916 · 294 km NE of this epicenter
- 7.388 km WSW of Adak, AlaskaJuly 7, 1929 · 235 km W of this epicenter
- 7.346 km SSW of Adak, AlaskaJune 10, 1996 · 178 km SW of this epicenter
- 7.3Fox Islands, Aleutian Islands, AlaskaJune 24, 2011 · 186 km E of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 10 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 · 109 km away
2 deathsSevere damage ($5–24M)tsunami
- 1986M8.0
Aleutian Islands: Adak
7 May 1986 · 79 km away · intensity VI
Moderate damage ($1–5M)tsunami
- 1901M7.8
Aleutian Islands: Fox Islands
31 Dec 1901 · 257 km away
Limited damage (under $1M)tsunami
- 1996M7.9
Andreanof Islands
10 Jun 1996 · 224 km away · intensity VI
tsunami
- 1996M7.3
Andreanof Islands
10 Jun 1996 · 178 km away
tsunami
- 2011M7.3
Aleutian Islands: Fox Islands
24 Jun 2011 · 186 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.