Reviewed by USGSJapan122y ago
M6.6 earthquake 132 km ESE of Iwaki, Japan
Sunday, April 8, 1906, 17:37:51 UTC · 36.723°N, 142.318°E
A magnitude 6.6 earthquake struck 132 km ESE of Iwaki, Japan on Sunday, April 8, 1906, 17:37:51 UTC, at a depth of 35.0 km (shallow). It is the strongest earthquake within 300 km since an M7.7 on July 6, 1905.
- 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
124 kilotons of TNT
That is about 8 times the Hiroshima bomb. It released about 260 times the energy of a magnitude 5.0.
Tectonic setting
71 km
from the nearest mapped plate boundary, between the Pacific and Okhotsk plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
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 5 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.7217 km ESE of Kamaishi, JapanJuly 6, 1905 · 246 km NE of this epicenter
- 7.0Northern Honshu, JapanMay 11, 1900 · 245 km NW of this epicenter
- 7.0Near the east coast of Honshu, JapanJune 15, 1901 · 260 km N of this epicenter
- 7.0Off the east coast of Honshu, JapanMay 2, 1902 · 293 km NE of this epicenter
- 6.3116 km ESE of Katsuura, JapanFebruary 24, 1906 · 246 km S of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 23 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 14,338 recorded deaths. The most severe:
- 1855M7.0
Tokyo
11 Nov 1855 · 256 km away
6,757 deathsExtreme damage ($25M+)tsunami
- 1703M8.2
Off Sw Boso Peninsula
30 Dec 1703 · 283 km away
5,233 deathsExtreme damage ($25M+)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 · 247 km away
745 deathsSevere damage ($5–24M)tsunami
- 1853
Odawara
11 Mar 1853 · 287 km away
79 deathsSevere damage ($5–24M)
- 1905M7.0
Off Fukushima
6 Jul 1905 · 79 km away
57 deathstsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.