Reviewed by USGSJapan89y ago
M5.8 earthquake 59 km E of Iwaki, Japan
Friday, December 23, 1938, 01:51:39 UTC · 37.048°N, 141.552°E
A magnitude 5.8 earthquake struck 59 km E of Iwaki, Japan on Friday, December 23, 1938, 01:51:39 UTC, at a depth of 25.0 km (shallow). It is the strongest earthquake within 300 km since an M6.0 on December 20, 1938.
- Magnitude
- 5.8
- Moderate · 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 earthquake
In context
How big was it, and why here?
Energy released
7 kilotons of TNT
That is about 1/2 of the Hiroshima bomb. It released about 14 times the energy of a magnitude 5.0.
Tectonic setting
143 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
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 75 km
USGS has not published any M2.5+ earthquake within 75 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 198 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 · 280 km SW of this epicenter
- 7.85 km E of Tateyama, JapanSeptember 2, 1923 · 272 km SW of this epicenter
- 7.8105 km E of Iwaki, JapanNovember 5, 1938 · 46 km E of this epicenter
- 7.7116 km E of Namie, JapanNovember 6, 1938 · 76 km NE of this epicenter
- 7.769 km ESE of Kitaibaraki, JapanMay 23, 1938 · 58 km S of this epicenter
- 7.7116 km ESE of Namie, JapanNovember 5, 1938 · 62 km E of this epicenter
- 7.7217 km ESE of Kamaishi, JapanJuly 6, 1905 · 272 km NE of this epicenter
- 7.6119 km SE of Kamaishi, JapanNovember 1, 1915 · 220 km NE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 51 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 121,128 recorded deaths. The most severe:
- 1923M7.9
Tokyo, Yokohama
1 Sep 1923 · 284 km away
105,385 deaths$600 million damagetsunami
- 1855M7.0
Tokyo
11 Nov 1855 · 221 km away
6,757 deathsExtreme damage ($25M+)tsunami
- 1703M8.2
Off Sw Boso Peninsula
30 Dec 1703 · 267 km away
5,233 deathsExtreme damage ($25M+)tsunami
- 1828
Sandyo In Etigo
18 Dec 1828 · 188 km away
1,443 deathsExtreme damage ($25M+)tsunami
- 1793M8.3
Sanriku,Rikuzen,Rikuchu
17 Feb 1793 · 269 km away
745 deathsSevere damage ($5–24M)tsunami
- 1894M7.0
Syonai
22 Oct 1894 · 257 km away
726 deathsSevere damage ($5–24M)tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.