M7.9 earthquake 174 km SE of Katsuura, Japan

Wednesday, November 25, 1953, 17:48:55 UTC · 34.006°N, 141.625°E

A magnitude 7.9 earthquake struck 174 km SE of Katsuura, Japan on Wednesday, November 25, 1953, 17:48:55 UTC, at a depth of 25.0 km (shallow). It is the strongest earthquake within 300 km since an M8.0 on September 1, 1923.

Magnitude: 7.9; Major · mw
Depth: 25 km; Shallow
Felt reports: 0; Did You Feel It?
Est. shaking: V; Moderate (ShakeMap)
PAGER alert: None; Not issued
Tsunami: No flag; USGS feed

Outlined circle: this earthquakeDashed circle: 200 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

11 megatons of TNT

That is about 709 times the Hiroshima bomb. It released about 22,387 times the energy of a magnitude 5.0.

Tectonic setting

23 km

from the nearest mapped plate boundary, between the Philippine Sea and Pacific plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.

Depth: shallow

25 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 8 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M6.7 on November 26, 1953. 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 173 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 22 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 117,755 recorded deaths. The most severe:

1923M7.9
Tokyo, Yokohama
1 Sep 1923 · 229 km away
105,385 deaths$600 million damagetsunami
1855M7.0
Tokyo
11 Nov 1855 · 247 km away
6,757 deathsExtreme damage ($25M+)tsunami
1703M8.2
Off Sw Boso Peninsula
30 Dec 1703 · 185 km away
5,233 deathsExtreme damage ($25M+)tsunami
1930M7.1
Honshu: Idu
25 Nov 1930 · 265 km away
259 deathsExtreme damage ($25M+)
1853
Odawara
11 Mar 1853 · 256 km away
79 deathsSevere damage ($5–24M)
1894M7.5
Tokyo
20 Jun 1894 · 245 km away
24 deathsLimited damage (under $1M)

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

Nearby trackers