Reviewed by USGSAlaska11y ago
M4.2 earthquake in Rat Islands, Aleutian Islands, Alaska
Sunday, April 19, 2015, 11:21:58 UTC · 51.804°N, 177.463°E
A magnitude 4.2 earthquake struck in Rat Islands, Aleutian Islands, Alaska on Sunday, April 19, 2015, 11:21:58 UTC, at a depth of 63.8 km (shallow).
- Magnitude
- 4.2
- Light · mb
- Depth
- 64 km
- Shallow
- Felt reports
- 0
- Max intensity I
- 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
30 tons of TNT
That is about 1/500 of the Hiroshima bomb. A magnitude 5.0 releases about 16 times more energy.
Tectonic setting
111 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
64 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 M4.1 on April 26, 2015. 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 821 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 · 106 km SE of this epicenter
- 8.31906 Western Aleutian Islands (Hawadax/Rat Islands) EarthquakeAugust 17, 1906 · 50 km E of this epicenter
- 7.9Rat Islands, Aleutian Islands, AlaskaJune 23, 2014 · 88 km E of this epicenter
- 7.8Rat Islands, Aleutian Islands, AlaskaNovember 17, 2003 · 110 km SE of this epicenter
- 7.6Rat Islands, Aleutian Islands, AlaskaMarch 30, 1965 · 171 km S of this epicenter
- 7.4265 km WSW of Adak, AlaskaFebruary 4, 1965 · 153 km E of this epicenter
- 7.2238 km SSE of Attu Station, AlaskaSeptember 8, 1939 · 195 km SW of this epicenter
- 7.2207 km WSW of Adak, AlaskaDecember 19, 2007 · 215 km E 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 · 106 km away · intensity VI
Under $1 million damagetsunami
- 1906M8.3
Aleutian Islands: Rat Islands
17 Aug 1906 · 50 km away
- 2014M7.9
Aleutian Islands
23 Jun 2014 · 88 km away · intensity VI
tsunami
- 1909M7.8
Aleutian Islands
10 Apr 1909 · 170 km away
- 2003M7.8
Aleutian Islands: Rat Islands
17 Nov 2003 · 110 km away
tsunami
- 1965M7.6
Aleutian Islands: Rat Islands
30 Mar 1965 · 168 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.