Reviewed by USGSJapan59y ago
M6.4 earthquake 182 km ESE of Kamaishi, Japan
Monday, June 17, 1968, 18:57:30 UTC · 38.701°N, 143.843°E
A magnitude 6.4 earthquake struck 182 km ESE of Kamaishi, Japan on Monday, June 17, 1968, 18:57:30 UTC, at a depth of 24.8 km (shallow). It is the strongest earthquake within 300 km since an M7.0 on June 12, 1968.
- Magnitude
- 6.4
- Strong · mw
- Depth
- 25 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: 100 km aftershock search area
In context
How big was it, and why here?
Energy released
60 kilotons of TNT
That is about 4 times the Hiroshima bomb. It released about 126 times the energy of a magnitude 5.0.
Tectonic setting
18 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
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 100 km
USGS lists 1 M2.5+ earthquake within 100 km in the following 30 days; the largest was M5.5 on June 30, 1968. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 382 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.41933 Sanriku (Sanriku-oki) Earthquake, JapanMarch 2, 1933 · 86 km NE of this epicenter
- 8.21968 Tokachi-Oki EarthquakeMay 16, 1968 · 247 km N of this epicenter
- 8.0113 km ENE of Miyako, JapanMarch 20, 1960 · 140 km N of this epicenter
- 7.978 km E of Hachinohe, JapanMarch 9, 1931 · 243 km NW of this epicenter
- 7.8105 km E of Iwaki, JapanNovember 5, 1938 · 248 km SW of this epicenter
- 7.7277 km SSE of Kushiro, JapanMay 3, 1919 · 265 km NE of this epicenter
- 7.7116 km E of Namie, JapanNovember 6, 1938 · 199 km SW of this epicenter
- 7.7116 km ESE of Namie, JapanNovember 5, 1938 · 223 km SW of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 55 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 31,250 recorded deaths. The most severe:
- 1896M8.3
Sanriku
15 Jun 1896 · 90 km away
27,122 deathsExtreme damage ($25M+)tsunami
- 1933M8.4
Sanriku
2 Mar 1933 · 86 km away
3,022 deathsExtreme damage ($25M+)tsunami
- 1793M8.3
Sanriku,Rikuzen,Rikuchu
17 Feb 1793 · 26 km away
745 deathsSevere damage ($5–24M)tsunami
- 1896
Senhoku, Ugo
31 Aug 1896 · 284 km away
206 deathsExtreme damage ($25M+)
- 1905M7.0
Off Fukushima
6 Jul 1905 · 181 km away
57 deathstsunami
- 1968M8.2
Off East Coast Of Honshu Island
16 May 1968 · 240 km away · intensity VI
52 deaths$131 million damagetsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.