M7.0 earthquake 118 km E of Miyako, Japan

Wednesday, March 23, 1960, 00:23:28 UTC · 39.635°N, 143.316°E

A magnitude 7.0 earthquake struck 118 km E of Miyako, Japan on Wednesday, March 23, 1960, 00:23:28 UTC, at a depth of 15.0 km (shallow). It is the strongest earthquake within 300 km since an M8.0 on March 20, 1960.

Magnitude: 7.0; Major · mw
Depth: 15 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

494 kilotons of TNT

That is about 33 times the Hiroshima bomb. It released about 1,035 times the energy of a magnitude 5.0.

Tectonic setting

78 km

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

Depth: shallow

15 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 5 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M6.4 on March 23, 1960. 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 304 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 51 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 33,438 recorded deaths. The most severe:

1896M8.3
Sanriku
15 Jun 1896 · 61 km away
27,122 deathsExtreme damage ($25M+)tsunami
1933M8.4
Sanriku
2 Mar 1933 · 119 km away
3,022 deathsExtreme damage ($25M+)tsunami
1766M6.9
Hirosaki
8 Mar 1766 · 263 km away
1,700 deathsSevere damage ($5–24M)tsunami
1793M8.3
Sanriku,Rikuzen,Rikuchu
17 Feb 1793 · 139 km away
745 deathsSevere damage ($5–24M)tsunami
1804M7.3
Kisakata
10 Jul 1804 · 297 km away
450 deathsExtreme damage ($25M+)tsunami
1896
Senhoku, Ugo
31 Aug 1896 · 202 km away
206 deathsExtreme damage ($25M+)

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

Nearby trackers