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The 1847 Nagano earthquake kills thousands in Japan

When
1847
Where
Nagano, Japan; Sai River
Episodes
2

The 1847 Zenkoji earthquake struck Nagano, Japan, on 8 May at approximately 21:30 local time. With a surface-wave magnitude of 7.4, the event resulted in widespread destruction of houses and at least 8,600 fatalities.

Episodes

  1. late May 1847, 19 days after 8 May · Sai River1847 Zenkoji Earthquake Dam Failure

    A landslide dam on the Sai River failed 19 days after the earthquake, causing a flood that killed 35 people.

  2. 8 May 1847 · Nagano, Japan1847 Zenkoji Earthquake

    A magnitude 7.4 earthquake struck Nagano, Japan, on 8 May, causing house destruction and at least 8,600 deaths.

Background and detail

Background. The 1847 Zenkoji earthquake occurred at about 21:30 local time on 8 May at Nagano, Japan. The seismic event had a magnitude of 7.4 on the surface-wave magnitude scale. It was caused by rupture on part of a fault zone, leading to significant geological disruption in the region.

Impact. The earthquake caused the destruction of many houses in Nagano. At least 8,600 people were killed as a result of the disaster. The high casualty count reflects the severity of the structural damage.

Aftermath. The earthquake triggered many landslides, the largest of which dammed the Sai River, a tributary of the Shinano River. 19 days later, the failure of this earthquake dam caused a flood that destroyed many more houses and killed 35 people.

Sources

  1. 1847 Zenkoji earthquake Wikipedia, revision of 2026-07-26

Machine-drafted from the cited Wikipedia passages and checked by a reviewing model, not by a human editor. Every passage cites the revision it was written from; dates and places follow those passages.