Reviewed by USGSAlaska23y ago
M3.6 earthquake in Rat Islands, Aleutian Islands, Alaska
Wednesday, January 21, 2004, 10:20:40 UTC · 50.470°N, 177.762°E
A magnitude 3.6 earthquake struck in Rat Islands, Aleutian Islands, Alaska on Wednesday, January 21, 2004, 10:20:40 UTC, at a depth of 1.0 km (shallow).
- Magnitude
- 3.6
- Minor · ml
- Depth
- 1 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
4 tons of TNT
That is about 1/3,975 of the Hiroshima bomb. A magnitude 5.0 releases about 126 times more energy.
Tectonic setting
24 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
1 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 1 M2.5+ earthquake within 50 km in the following 30 days; the largest was M3.2 on January 21, 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 590 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 · 110 km NE of this epicenter
- 8.31906 Western Aleutian Islands (Hawadax/Rat Islands) EarthquakeAugust 17, 1906 · 157 km N of this epicenter
- 7.8Rat Islands, Aleutian Islands, AlaskaNovember 17, 2003 · 98 km NE of this epicenter
- 7.6Rat Islands, Aleutian Islands, AlaskaMarch 30, 1965 · 22 km S of this epicenter
- 7.4265 km WSW of Adak, AlaskaFebruary 4, 1965 · 167 km NE of this epicenter
- 7.2238 km SSE of Attu Station, AlaskaSeptember 8, 1939 · 206 km W of this epicenter
- 7.2238 km WSW of Adak, AlaskaMarch 22, 1905 · 183 km NE of this epicenter
- 7.2162 km WSW of Adak, AlaskaMarch 16, 1957 · 258 km NE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 9 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1965M8.7
Aleutian Islands: Rat Islands
4 Feb 1965 · 110 km away · intensity VI
Under $1 million damagetsunami
- 1906M8.3
Aleutian Islands: Rat Islands
17 Aug 1906 · 157 km away
- 1905M7.9
Andreanof Islands
14 Feb 1905 · 262 km away
- 1909M7.8
Aleutian Islands
10 Apr 1909 · 257 km away
- 2003M7.8
Aleutian Islands: Rat Islands
17 Nov 2003 · 98 km away
tsunami
- 1916M7.7
Aleutian Islands
6 Feb 1916 · 225 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.