Reviewed by USGSJapan83y ago
M6.9 earthquake off the east coast of Honshu, Japan
Wednesday, July 19, 1944, 10:21:20 UTC · 33.806°N, 141.594°E
A magnitude 6.9 earthquake struck off the east coast of Honshu, Japan on Wednesday, July 19, 1944, 10:21:20 UTC, at a depth of 15.0 km (shallow). It is the strongest earthquake within 300 km since an M7.1 on April 11, 1943.
- Magnitude
- 6.9
- 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 earthquakeDashed circle: 100 km aftershock search area
In context
How big was it, and why here?
Energy released
326 kilotons of TNT
That is about 22 times the Hiroshima bomb. It released about 684 times the energy of a magnitude 5.0.
Tectonic setting
25 km
from the nearest mapped plate boundary, between the Philippine Sea and Pacific 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 lists 1 M2.5+ earthquake within 100 km in the following 30 days; the largest was M6.1 on July 20, 1944. 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 145 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.05 km SSE of Ōiso, JapanSeptember 1, 1923 · 263 km NW of this epicenter
- 7.85 km E of Tateyama, JapanSeptember 2, 1923 · 201 km NW of this epicenter
- 7.3190 km SE of Hasaki, JapanSeptember 7, 1906 · 136 km NE of this epicenter
- 7.264 km ENE of Hasaki, JapanJune 1, 1923 · 237 km N of this epicenter
- 7.238 km SSW of Shimoda, JapanOctober 24, 1905 · 260 km W of this epicenter
- 7.196 km ESE of Takahagi, JapanApril 11, 1943 · 278 km N of this epicenter
- 7.167 km ENE of Kashima-shi, JapanAugust 14, 1924 · 267 km N of this epicenter
- 7.1150 km ESE of Hasaki, JapanMarch 13, 1909 · 178 km NE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 18 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 117,754 recorded deaths. The most severe:
- 1923M7.9
Tokyo, Yokohama
1 Sep 1923 · 240 km away
105,385 deaths$600 million damagetsunami
- 1855M7.0
Tokyo
11 Nov 1855 · 263 km away
6,757 deathsExtreme damage ($25M+)tsunami
- 1703M8.2
Off Sw Boso Peninsula
30 Dec 1703 · 198 km away
5,233 deathsExtreme damage ($25M+)tsunami
- 1930M7.1
Honshu: Idu
25 Nov 1930 · 273 km away
259 deathsExtreme damage ($25M+)
- 1853
Odawara
11 Mar 1853 · 269 km away
79 deathsSevere damage ($5–24M)
- 1894M7.5
Tokyo
20 Jun 1894 · 261 km away
24 deathsLimited damage (under $1M)
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.