Reviewed by USGSAlaska22y ago
M2.5 earthquake 12 km SSW of Atka, Alaska
Wednesday, October 27, 2004, 17:38:43 UTC · 52.089°N, 174.243°W
A magnitude 2.5 earthquake struck 12 km SSW of Atka, Alaska on Wednesday, October 27, 2004, 17:38:43 UTC, at a depth of 198.1 km (intermediate).
- Magnitude
- 2.5
- Minor · ml
- Depth
- 198 km
- Intermediate
- 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: 50 km aftershock search area
In context
How big was it, and why here?
Energy released
85 kg of TNT
That is about 1/177,558 of the Hiroshima bomb. A magnitude 5.0 releases about 5,623 times more energy.
Tectonic setting
131 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
198 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 1 M2.5+ earthquake within 50 km in the following 30 days; the largest was M3.8 on November 17, 2004. 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 800 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 · 116 km SW of this epicenter
- 8.01986 Atka, Alaska EarthquakeMay 7, 1986 · 73 km SW of this epicenter
- 7.977 km WSW of Adak, AlaskaJune 10, 1996 · 240 km W of this epicenter
- 7.65 km WNW of Adak, AlaskaFebruary 14, 1905 · 170 km W of this epicenter
- 7.4133 km WNW of Nikolski, AlaskaApril 18, 1916 · 284 km NE of this epicenter
- 7.388 km WSW of Adak, AlaskaJuly 7, 1929 · 250 km W of this epicenter
- 7.346 km SSW of Adak, AlaskaJune 10, 1996 · 192 km W of this epicenter
- 7.175 km S of Adak, AlaskaMarch 14, 1957 · 198 km SW of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 8 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 · 116 km away
2 deathsSevere damage ($5–24M)tsunami
- 1986M8.0
Aleutian Islands: Adak
7 May 1986 · 73 km away · intensity VI
Moderate damage ($1–5M)tsunami
- 1901M7.8
Aleutian Islands: Fox Islands
31 Dec 1901 · 233 km away
Limited damage (under $1M)tsunami
- 1996M7.9
Andreanof Islands
10 Jun 1996 · 240 km away · intensity VI
tsunami
- 1996M7.3
Andreanof Islands
10 Jun 1996 · 192 km away
tsunami
- 1971M7.1
Andreanof Islands
2 May 1971 · 218 km away · intensity VI
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.