Reviewed by USGSAlaska22y ago
M3.9 earthquake in Rat Islands, Aleutian Islands, Alaska
Friday, October 15, 2004, 01:24:42 UTC · 51.824°N, 178.127°E
A magnitude 3.9 earthquake struck in Rat Islands, Aleutian Islands, Alaska on Friday, October 15, 2004, 01:24:42 UTC, at a depth of 65.5 km (shallow).
- Magnitude
- 3.9
- Minor · mb
- Depth
- 66 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 earthquake
In context
How big was it, and why here?
Energy released
11 tons of TNT
That is about 1/1,410 of the Hiroshima bomb. A magnitude 5.0 releases about 45 times more energy.
Tectonic setting
128 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: shallow
66 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 has not published any M2.5+ earthquake within 50 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 709 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 · 76 km SE of this epicenter
- 8.31906 Western Aleutian Islands (Hawadax/Rat Islands) EarthquakeAugust 17, 1906 · 5 km NE of this epicenter
- 7.977 km WSW of Adak, AlaskaJune 10, 1996 · 294 km E of this epicenter
- 7.8Rat Islands, Aleutian Islands, AlaskaNovember 17, 2003 · 84 km SE of this epicenter
- 7.6Rat Islands, Aleutian Islands, AlaskaMarch 30, 1965 · 172 km S of this epicenter
- 7.4265 km WSW of Adak, AlaskaFebruary 4, 1965 · 110 km SE of this epicenter
- 7.388 km WSW of Adak, AlaskaJuly 7, 1929 · 287 km E of this epicenter
- 7.2238 km SSE of Attu Station, AlaskaSeptember 8, 1939 · 238 km W 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 · 76 km away · intensity VI
Under $1 million damagetsunami
- 1906M8.3
Aleutian Islands: Rat Islands
17 Aug 1906 · 5 km away
- 1905M7.9
Andreanof Islands
14 Feb 1905 · 261 km away
- 1996M7.9
Andreanof Islands
10 Jun 1996 · 294 km away · intensity VI
tsunami
- 1909M7.8
Aleutian Islands
10 Apr 1909 · 215 km away
- 2003M7.8
Aleutian Islands: Rat Islands
17 Nov 2003 · 84 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.