M7.2 earthquake 134 km E of Shikotan, Russia

Saturday, December 21, 1946, 10:18:47 UTC · 43.658°N, 148.376°E

A magnitude 7.2 earthquake struck 134 km E of Shikotan, Russia on Saturday, December 21, 1946, 10:18:47 UTC, at a depth of 20.0 km (shallow). It is the strongest earthquake within 300 km since an M7.4 on February 21, 1937.

Magnitude: 7.2; Major · mw
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: 200 km aftershock search area

In context

How big was it, and why here?

Energy released

951 kilotons of TNT

That is about 63 times the Hiroshima bomb. It released about 1,995 times the energy of a magnitude 5.0.

Tectonic setting

38 km

from the nearest mapped plate boundary, between the Okhotsk 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 200 km

USGS lists 6 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M6.8 on December 21, 1946. 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 112 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 15 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 58 recorded deaths. The most severe:

1843M8.4
Hokkaido: Yezo, Kushiro, Nemuro
25 Apr 1843 · 267 km away
45 deathsModerate damage ($1–5M)tsunami
1780M7.5
Kuril Islands
29 Jun 1780 · 289 km away
12 deathsLimited damage (under $1M)tsunami
1894M7.9
Off Coast Of Honshu
22 Mar 1894 · 232 km away · intensity IX
1 deathModerate damage ($1–5M)tsunami
1904M7.6
Hokkaido
18 Mar 1904 · 246 km away · intensity X
Limited damage (under $1M)
1937M7.6
Kuril Islands
21 Feb 1937 · 124 km away
Limited damage (under $1M)
1900M7.9
Kuril Islands
25 Dec 1900 · 206 km away · intensity IX

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

Nearby trackers