M5.0 earthquake 71 km S of King Cove, Alaska

Sunday, January 24, 2021, 21:16:22 UTC · 54.425°N, 162.169°W

A magnitude 5.0 earthquake struck 71 km S of King Cove, Alaska on Sunday, January 24, 2021, 21:16:22 UTC, at a depth of 39.4 km (shallow). USGS received 6 “Did You Feel It?” reports, with a maximum reported intensity of IV (light). It is the strongest earthquake within 300 km since an M5.1 on January 11, 2021.

Magnitude: 5.0; Moderate · mww
Depth: 39 km; Shallow
Felt reports: 6; Max intensity IV
Est. shaking: —; No ShakeMap
PAGER alert: None; Not issued
Tsunami: No flag; USGS feed

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

In context

How big was it, and why here?

Energy released

477 tons of TNT

That is about 1/32 of the Hiroshima bomb. Each whole step in magnitude is about 32 times more energy.

Tectonic setting

107 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

39 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

Reports sent by people to USGS, grouped by place (most reports first). Intensity uses the Modified Mercalli scale (I–X): what people felt, not the magnitude.

Place	Intensity	Reports	Distance
99612<br>0.293	IV · Light	5	113 km
99661<br>0.330	IV · Light	1	140 km

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 75 km

USGS lists 15 M2.5+ earthquakes within 75 km in the following 30 days; the largest was M4.8 on February 6, 2021. 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 383 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 11 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 168 recorded deaths. The most severe:

1946M8.6
Unimak Island
1 Apr 1946 · 112 km away · intensity VI
168 deaths$26 million damagetsunami
2020M7.8
Alaska
22 Jul 2020 · 240 km away · intensity VII
Limited damage (under $1M)tsunami
1938M8.2
Alaska
10 Nov 1938 · 269 km away · intensity VI
tsunami
2021M8.2
Alaska Peninsula
29 Jul 2021 · 294 km away · intensity VIII
tsunami
1788M8.0
Alaska Peninsula
6 Aug 1788 · 99 km away
tsunami
2020M7.6
Alaska
19 Oct 2020 · 165 km away · intensity IX
tsunami

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

Nearby trackers