Reviewed by USGSAlaska10y ago
M4.0 earthquake 61 km ENE of Atka, Alaska
Friday, December 25, 2015, 07:11:05 UTC · 52.464°N, 173.419°W
A magnitude 4.0 earthquake struck 61 km ENE of Atka, Alaska on Friday, December 25, 2015, 07:11:05 UTC, at a depth of 186.2 km (intermediate).
- Magnitude
- 4.0
- Light · mb
- Depth
- 186 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
164 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
186 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 2 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M3.0 on January 5, 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 898 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 · 185 km SW of this epicenter
- 8.01986 Atka, Alaska EarthquakeMay 7, 1986 · 140 km SW of this epicenter
- 7.65 km WNW of Adak, AlaskaFebruary 14, 1905 · 233 km W of this epicenter
- 7.4133 km WNW of Nikolski, AlaskaApril 18, 1916 · 214 km NE of this epicenter
- 7.346 km SSW of Adak, AlaskaJune 10, 1996 · 259 km SW of this epicenter
- 7.3Fox Islands, Aleutian Islands, AlaskaJune 24, 2011 · 117 km SE of this epicenter
- 7.175 km S of Adak, AlaskaMarch 14, 1957 · 268 km SW of this epicenter
- 7.160 km SW of Adak, AlaskaMarch 12, 1957 · 284 km W of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 13 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 · 185 km away
2 deathsSevere damage ($5–24M)tsunami
- 1986M8.0
Aleutian Islands: Adak
7 May 1986 · 140 km away · intensity VI
Moderate damage ($1–5M)tsunami
- 1901M7.8
Aleutian Islands: Fox Islands
31 Dec 1901 · 199 km away
Limited damage (under $1M)tsunami
- 1907M7.8
Aleutian Islands
2 Sep 1907 · 250 km away
- 1929M7.8
Aleutian Islands: Fox Islands
7 Mar 1929 · 286 km away · intensity V
tsunami
- 1916M7.5
Aleutian Islands: Fox Islands
18 Apr 1916 · 248 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.