Reviewed by USGSJapan87y ago
M7.5 earthquake 137 km WSW of Rishiri Town, Japan
Thursday, August 1, 1940, 15:08:24 UTC · 44.561°N, 139.678°E
A magnitude 7.5 earthquake struck 137 km WSW of Rishiri Town, Japan on Thursday, August 1, 1940, 15:08:24 UTC, at a depth of 15.0 km (shallow). No earthquake of this size or larger appears within 300 km in the USGS catalog since 1900.
- Magnitude
- 7.5
- Major · mw
- Depth
- 15 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- V
- Moderate (ShakeMap)
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeColoured lines: estimated shaking intensity (USGS ShakeMap)
In context
How big was it, and why here?
Energy released
2.7 megatons of TNT
That is about 178 times the Hiroshima bomb. It released about 5,623 times the energy of a magnitude 5.0.
Tectonic setting
71 km
from the nearest mapped plate boundary, between the Okhotsk and Amur 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 200 km
USGS has not published any M2.5+ earthquake within 200 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 8 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.322 km ESE of Makubetsu, JapanSeptember 1, 1905 · 207 km NE of this epicenter
- 7.079 km S of Korsakov, RussiaSeptember 6, 1911 · 291 km NE of this epicenter
- 6.830 km ESE of Tomakomai, JapanFebruary 20, 1913 · 291 km SE of this epicenter
- 6.225 km WSW of Muroran, JapanJune 8, 1912 · 274 km S of this epicenter
- 6.070 km WSW of Niseko Town, JapanFebruary 4, 1926 · 226 km S of this epicenter
- 6.093 km WNW of Rumoi, JapanSeptember 8, 1910 · 78 km SE of this epicenter
- 6.017 km ESE of Asahikawa, JapanJuly 11, 1927 · 249 km E of this epicenter
- 5.983 km NNE of Nayoro, JapanJanuary 31, 1932 · 251 km E of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 6 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 10 recorded deaths. The most severe:
- 1940M7.5
W. Hokkaido Island
1 Aug 1940 · 43 km away · intensity IX
10 deathsModerate damage ($1–5M)tsunami
- 1792M6.9
W. Hokkaido Island
13 Jun 1792 · 139 km away
Limited damage (under $1M)tsunami
- 1834M6.4
W. Hokkaido Island, Japan
9 Feb 1834 · 197 km away
Limited damage (under $1M)tsunami
- 1918M7.7
E Coast Of
30 Jan 1918 · 267 km away
- 1905M7.5
Hokkaido
1 Sep 1905 · 267 km away
- 1863M6.4
Nw. Hokkaido Island, Japan
20 Sep 1863 · 144 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.