The strongest earthquake to hit the Tokyo area since the 2011 Tohoku earthquake, registering magnitude 5.9 at shallow-intermediate depth.
Key Facts
- Magnitude
- 5.9 Richter scale
- Depth
- 62–75 km
- Maximum Shindo Intensity
- 5+
- Mercalli Intensity
- VI (Strong)
- Epicenter Distance from Chiba
- ~4 km southwest
- Time of Occurrence
- 22:41 JST, October 7, 2021
By the Numbers
Location
Cause → Event → Consequence
The earthquake originated from tectonic stress at a depth of approximately 62 to 75 kilometers beneath Chiba Prefecture, in a seismically active zone where the Philippine Sea Plate subducts beneath the Eurasian Plate in the greater Tokyo metropolitan region.
On October 7, 2021, at 22:41 JST, a magnitude 5.9 earthquake struck approximately 4 kilometers southwest of Chiba city. It reached a maximum seismic intensity of Shindo 5+, equivalent to VI (Strong) on the Mercalli scale, and was felt broadly across the Tokyo metropolitan area.
The earthquake was notable as the strongest to affect the Tokyo area since the catastrophic 2011 Tohoku earthquake, prompting concern among residents and authorities. Its relatively deep focus limited surface damage, but the event underscored the persistent seismic hazard facing Japan's most densely populated region.