Reviewed by USGSAlaska18y ago
M2.5 earthquake 257 km ESE of Attu Station, Alaska
Friday, August 29, 2008, 08:41:30 UTC · 51.731°N, 176.500°E
A magnitude 2.5 earthquake struck 257 km ESE of Attu Station, Alaska on Friday, August 29, 2008, 08:41:30 UTC, at a depth of 19.9 km (shallow).
- Magnitude
- 2.5
- Minor · ml
- Depth
- 20 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
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
84 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
20 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 4 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M3.9 on September 9, 2008. 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 601 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 · 162 km E of this epicenter
- 8.31906 Western Aleutian Islands (Hawadax/Rat Islands) EarthquakeAugust 17, 1906 · 116 km E of this epicenter
- 7.8Rat Islands, Aleutian Islands, AlaskaNovember 17, 2003 · 163 km SE of this epicenter
- 7.6Rat Islands, Aleutian Islands, AlaskaMarch 30, 1965 · 187 km SE of this epicenter
- 7.636 km NE of Attu Station, AlaskaFebruary 2, 1975 · 255 km NW of this epicenter
- 7.4265 km WSW of Adak, AlaskaFebruary 4, 1965 · 216 km E of this epicenter
- 7.4151 km S of Attu Station, AlaskaSeptember 2, 1907 · 256 km W of this epicenter
- 7.2238 km SSE of Attu Station, AlaskaSeptember 8, 1939 · 134 km SW 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:
- 1975M7.6
Aleutian Islands: Near Islands
2 Feb 1975 · 255 km away · intensity IX
Moderate damage ($1–5M)
- 1965M8.7
Aleutian Islands: Rat Islands
4 Feb 1965 · 162 km away · intensity VI
Under $1 million damagetsunami
- 1906M8.3
Aleutian Islands: Rat Islands
17 Aug 1906 · 116 km away
- 1909M7.8
Aleutian Islands
10 Apr 1909 · 107 km away
- 2003M7.8
Aleutian Islands: Rat Islands
17 Nov 2003 · 163 km away
tsunami
- 1965M7.6
Aleutian Islands: Rat Islands
30 Mar 1965 · 186 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.