M5.6 earthquake 81 km E of Yamada, Japan

Saturday, June 15, 1968, 03:31:19 UTC · 39.411°N, 142.899°E

A magnitude 5.6 earthquake struck 81 km E of Yamada, Japan on Saturday, June 15, 1968, 03:31:19 UTC, at a depth of 20.3 km (shallow). It is the strongest earthquake within 300 km since an M5.7 on June 14, 1968.

Magnitude: 5.6; Moderate · 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: 75 km aftershock search area

In context

How big was it, and why here?

Energy released

4 kilotons of TNT

That is about 1/4 of the Hiroshima bomb. It released about 8 times the energy of a magnitude 5.0.

Tectonic setting

112 km

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

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 75 km

USGS lists 6 M2.5+ earthquakes within 75 km in the following 30 days; the largest was M6.0 on July 12, 1968. 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 419 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 65 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 34,318 recorded deaths. The most severe:

1896M8.3
Sanriku
15 Jun 1896 · 95 km away
27,122 deathsExtreme damage ($25M+)tsunami
1933M8.4
Sanriku
2 Mar 1933 · 147 km away
3,022 deathsExtreme damage ($25M+)tsunami
1766M6.9
Hirosaki
8 Mar 1766 · 250 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
1894M7.0
Syonai
22 Oct 1894 · 273 km away
726 deathsSevere damage ($5–24M)tsunami
1804M7.3
Kisakata
10 Jul 1804 · 257 km away
450 deathsExtreme damage ($25M+)tsunami

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

Nearby trackers