M8.1 earthquake 1952 Tokachi-Oki Earthquake

Tuesday, March 4, 1952, 01:22:49 UTC · 42.084°N, 143.899°E

A magnitude 8.1 earthquake struck 1952 Tokachi-Oki Earthquake on Tuesday, March 4, 1952, 01:22:49 UTC, at a depth of 45.0 km (shallow). No earthquake of this size or larger appears within 300 km in the USGS catalog since 1900.

Magnitude: 8.1; Great · mw
Depth: 45 km; Shallow
Felt reports: 0; Did You Feel It?
Est. shaking: VII; Very strong (ShakeMap)
PAGER alert: None; Not issued
Tsunami: No flag; USGS feed

Outlined circle: this earthquakeDashed circle: 400 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)

In context

How big was it, and why here?

Energy released

21 megatons of TNT

That is about 1,415 times the Hiroshima bomb. It released about 44,668 times the energy of a magnitude 5.0.

Tectonic setting

129 km

from the nearest mapped plate boundary, between the Okhotsk and Pacific plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.

Depth: shallow

45 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 400 km

USGS lists 13 M2.5+ earthquakes within 400 km in the following 30 days; the largest was M6.9 on March 9, 1952. 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 167 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 31 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 28,946 recorded deaths. The most severe:

1896M8.3
Sanriku
15 Jun 1896 · 287 km away
27,122 deathsExtreme damage ($25M+)tsunami
1766M6.9
Hirosaki
8 Mar 1766 · 297 km away
1,700 deathsSevere damage ($5–24M)tsunami
1843M8.4
Hokkaido: Yezo, Kushiro, Nemuro
25 Apr 1843 · 174 km away
45 deathsModerate damage ($1–5M)tsunami
1952M8.1
Hokkaido
4 Mar 1952 · 8 km away · intensity IX
33 deathsSevere damage ($5–24M)tsunami
1856M8.0
Oshima
23 Aug 1856 · 179 km away · intensity V
26 deathsModerate damage ($1–5M)tsunami
1901M8.2
Off Northeast Coast Honshu
9 Aug 1901 · 212 km away
18 deathsModerate damage ($1–5M)tsunami

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

Nearby trackers