Reviewed by USGSJapan110y ago
M6.8 earthquake 92 km NNE of Hirara, Japan
Wednesday, July 4, 1917, 05:36:35 UTC · 25.575°N, 125.647°E
A magnitude 6.8 earthquake struck 92 km NNE of Hirara, Japan on Wednesday, July 4, 1917, 05:36:35 UTC, at a depth of 15.0 km (shallow). It is the strongest earthquake within 300 km since an M7.3 on July 4, 1917.
- Magnitude
- 6.8
- Strong · mw
- Depth
- 15 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 earthquake
In context
How big was it, and why here?
Energy released
215 kilotons of TNT
That is about 14 times the Hiroshima bomb. It released about 452 times the energy of a magnitude 5.0.
Tectonic setting
6 km
from the nearest mapped plate boundary, between the Yangtze and Okinawa 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 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 10 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.11910 Taiwan EarthquakeApril 12, 1910 · 141 km W of this epicenter
- 7.3120 km ENE of Hirara, JapanJuly 4, 1917 · 92 km SE of this epicenter
- 7.392 km NNW of Yonakuni, JapanJanuary 5, 1915 · 287 km W of this epicenter
- 7.298 km SSW of Ishigaki, JapanFebruary 28, 1915 · 299 km SW of this epicenter
- 7.012 km SE of Ginowan, JapanFebruary 23, 1911 · 231 km E of this epicenter
- 6.859 km NE of Hirara, JapanNovember 29, 1910 · 40 km S of this epicenter
- 6.640 km ESE of Yonakuni, JapanDecember 24, 1912 · 275 km SW of this epicenter
- 6.588 km NW of Hirara, JapanMay 2, 1906 · 100 km W of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 5 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 13,486 recorded deaths. The most severe:
- 1771M7.4
Ryukyu Islands
24 Apr 1771 · 222 km away
13,486 deathsExtreme damage ($25M+)tsunami
- 1768M6.5
Ryukyu Islands
22 Jul 1768 · 198 km away
Limited damage (under $1M)tsunami
- 1917M7.7
Ne Of Taiwan
4 Jul 1917 · 274 km away
- 1853
Okinawa
3 Oct 1853 · 207 km away
tsunami
- 1858
Ryukyu Islands
Sep 1858 · 198 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.