Reviewed by USGSAlaska23y ago
M2.6 earthquake 227 km SW of Adak, Alaska
Thursday, December 18, 2003, 11:28:40 UTC · 50.752°N, 179.363°W
A magnitude 2.6 earthquake struck 227 km SW of Adak, Alaska on Thursday, December 18, 2003, 11:28:40 UTC, at a depth of 33.4 km (shallow).
- Magnitude
- 2.6
- Minor · ml
- Depth
- 33 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 earthquakeDashed circle: 50 km aftershock search area
In context
How big was it, and why here?
Energy released
120 kg of TNT
That is about 1/125,702 of the Hiroshima bomb. A magnitude 5.0 releases about 3,981 times more energy.
Tectonic setting
28 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
33 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 3 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M3.0 on January 6, 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 813 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.71965 Western Aleutian Islands (Hawadax/Rat Islands) EarthquakeFebruary 4, 1965 · 146 km NW of this epicenter
- 8.61957 Atka, Alaska EarthquakeMarch 9, 1957 · 274 km E of this epicenter
- 8.31906 Western Aleutian Islands (Hawadax/Rat Islands) EarthquakeAugust 17, 1906 · 210 km NW of this epicenter
- 7.977 km WSW of Adak, AlaskaJune 10, 1996 · 151 km NE of this epicenter
- 7.8Rat Islands, Aleutian Islands, AlaskaNovember 17, 2003 · 146 km W of this epicenter
- 7.6Rat Islands, Aleutian Islands, AlaskaMarch 30, 1965 · 202 km W of this epicenter
- 7.65 km WNW of Adak, AlaskaFebruary 14, 1905 · 224 km NE of this epicenter
- 7.4265 km WSW of Adak, AlaskaFebruary 4, 1965 · 105 km NW of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 12 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 · 274 km away
2 deathsSevere damage ($5–24M)tsunami
- 1965M8.7
Aleutian Islands: Rat Islands
4 Feb 1965 · 146 km away · intensity VI
Under $1 million damagetsunami
- 1906M8.3
Aleutian Islands: Rat Islands
17 Aug 1906 · 210 km away
- 1905M7.9
Andreanof Islands
14 Feb 1905 · 57 km away
- 1996M7.9
Andreanof Islands
10 Jun 1996 · 151 km away · intensity VI
tsunami
- 2003M7.8
Aleutian Islands: Rat Islands
17 Nov 2003 · 146 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.