M5.3 earthquake in Rat Islands, Aleutian Islands, Alaska

Thursday, October 29, 2015, 02:49:28 UTC · 51.814°N, 178.525°E

A magnitude 5.3 earthquake struck in Rat Islands, Aleutian Islands, Alaska on Thursday, October 29, 2015, 02:49:28 UTC, at a depth of 93.9 km (intermediate). The USGS PAGER alert is green: low likelihood of casualties and damage. It is the strongest earthquake within 300 km since an M5.7 on October 5, 2015.

Tsunami flagUSGS sets this flag for large events in oceanic regions so tsunami warning centers review them. It does not by itself mean a tsunami occurred. Check tsunami.gov and local authorities for official messages.

Magnitude: 5.3; Moderate · mww
Depth: 94 km; Intermediate
Felt reports: 0; Did You Feel It?
Est. shaking: —; No ShakeMap
PAGER alert: Green; Impact estimate
Tsunami: Flag; Check tsunami.gov

Outlined circle: this earthquakeDashed circle: 75 km aftershock search area

In context

How big was it, and why here?

Energy released

1 kilotons of TNT

That is about 1/11 of the Hiroshima bomb. It released about 3 times the energy of a magnitude 5.0.

Tectonic setting

131 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: intermediate

94 km

Intermediate-depth earthquakes usually break inside a plate that is sinking into the mantle. Shaking spreads over a wide area but is gentler at the epicenter than a shallow quake of the same size.

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 populated area was estimated to feel noticeable shaking.

After the main event

Aftershocks within 75 km

USGS lists 10 M2.5+ earthquakes within 75 km in the following 30 days; the largest was M4.3 on November 19, 2015. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.

Regional history

Past M5+ earthquakes within 300 km

USGS lists 913 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

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. The most severe:

1965M8.7
Aleutian Islands: Rat Islands
4 Feb 1965 · 64 km away · intensity VI
Under $1 million damagetsunami
1906M8.3
Aleutian Islands: Rat Islands
17 Aug 1906 · 24 km away
1905M7.9
Andreanof Islands
14 Feb 1905 · 236 km away
1996M7.9
Andreanof Islands
10 Jun 1996 · 266 km away · intensity VI
tsunami
2014M7.9
Aleutian Islands
23 Jun 2014 · 15 km away · intensity VI
tsunami
1909M7.8
Aleutian Islands
10 Apr 1909 · 243 km away

NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.

Nearby trackers