Reviewed by USGSJapan59y ago
M6.3 earthquake 68 km E of Onagawa Chō, Japan
Friday, July 5, 1968, 11:28:13 UTC · 38.497°N, 142.230°E
A magnitude 6.3 earthquake struck 68 km E of Onagawa Chō, Japan on Friday, July 5, 1968, 11:28:13 UTC, at a depth of 39.1 km (shallow). It is the strongest earthquake within 300 km since an M6.4 on June 17, 1968.
- Magnitude
- 6.3
- Strong · mw
- Depth
- 39 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- IV
- Light (ShakeMap)
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeColoured lines: estimated shaking intensity (USGS ShakeMap)
In context
How big was it, and why here?
Energy released
43 kilotons of TNT
That is about 3 times the Hiroshima bomb. It released about 89 times the energy of a magnitude 5.0.
Tectonic setting
152 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
39 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 has not published any M2.5+ earthquake within 100 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 456 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 · 219 km E of this epicenter
- 8.21968 Tokachi-Oki EarthquakeMay 16, 1968 · 283 km N of this epicenter
- 8.0113 km ENE of Miyako, JapanMarch 20, 1960 · 175 km NE of this epicenter
- 7.978 km E of Hachinohe, JapanMarch 9, 1931 · 233 km N of this epicenter
- 7.8105 km E of Iwaki, JapanNovember 5, 1938 · 170 km S of this epicenter
- 7.7116 km E of Namie, JapanNovember 6, 1938 · 124 km S of this epicenter
- 7.769 km ESE of Kitaibaraki, JapanMay 23, 1938 · 229 km S of this epicenter
- 7.7116 km ESE of Namie, JapanNovember 5, 1938 · 150 km S of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 69 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 35,870 recorded deaths. The most severe:
- 1896M8.3
Sanriku
15 Jun 1896 · 189 km away
27,122 deathsExtreme damage ($25M+)tsunami
- 1933M8.4
Sanriku
2 Mar 1933 · 219 km away
3,022 deathsExtreme damage ($25M+)tsunami
- 1766M6.9
Hirosaki
8 Mar 1766 · 298 km away
1,700 deathsSevere damage ($5–24M)tsunami
- 1828
Sandyo In Etigo
18 Dec 1828 · 264 km away
1,443 deathsExtreme damage ($25M+)tsunami
- 1793M8.3
Sanriku,Rikuzen,Rikuchu
17 Feb 1793 · 154 km away
745 deathsSevere damage ($5–24M)tsunami
- 1894M7.0
Syonai
22 Oct 1894 · 216 km away
726 deathsSevere damage ($5–24M)tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.