Reviewed by USGSJapan104y ago
M6.6 earthquake 28 km S of Nishinoomote, Japan
Friday, July 13, 1923, 23:56:21 UTC · 30.482°N, 131.048°E
A magnitude 6.6 earthquake struck 28 km S of Nishinoomote, Japan on Friday, July 13, 1923, 23:56:21 UTC, at a depth of 35.0 km (shallow). It is the strongest earthquake within 300 km since an M7.4 on July 13, 1923.
- Magnitude
- 6.6
- Strong · mw
- Depth
- 35 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
133 kilotons of TNT
That is about 9 times the Hiroshima bomb. It released about 279 times the energy of a magnitude 5.0.
Tectonic setting
122 km
from the nearest mapped plate boundary, between the Okinawa and Philippine Sea plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.
Depth: shallow
35 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 19 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.9108 km NW of Naze, JapanJune 15, 1911 · 263 km SW of this epicenter
- 7.518 km SE of Honmachi, JapanNovember 10, 1909 · 215 km N of this epicenter
- 7.4152 km ESE of Koshima, JapanFebruary 1, 1916 · 134 km SE of this epicenter
- 7.422 km N of Nishinoomote, JapanJuly 13, 1923 · 50 km N of this epicenter
- 7.229 km ESE of Takanabe, JapanApril 13, 1913 · 187 km N of this epicenter
- 7.2Ryukyu Islands, JapanJune 24, 1901 · 294 km S of this epicenter
- 7.161 km ESE of Nishinoomote, JapanAugust 24, 1904 · 49 km E of this epicenter
- 6.88 km NNE of Kajiki, JapanJanuary 12, 1914 · 151 km N of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 13 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 15,152 recorded deaths. The most severe:
- 1792M6.4
Kyusyu Island
21 May 1792 · 267 km away
15,030 deathsExtreme damage ($25M+)tsunami
- 1914M7.1
Sakurijima
12 Jan 1914 · 127 km away
63 deaths$19 million damagetsunami
- 1922
Kyushu
7 Dec 1922 · 257 km away
27 deathsLimited damage (under $1M)
- 1889M6.3
Kumamoto
28 Jul 1889 · 260 km away
20 deathsLimited damage (under $1M)
- 1911M8.0
Ryukyu Islands
15 Jun 1911 · 294 km away
12 deathsSevere damage ($5–24M)tsunami
- 1769M7.4
Sw. Kyushu Island, Japan
29 Aug 1769 · 221 km away
Moderate damage ($1–5M)tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.