Akahoya eruption (jan 1, 4350 BC – jan 1, 4300 BC)
Description:
...creates the Kikai Caldera and ends the earliest homogeneous Jomon culture in Japan. When the Jomon culture recovers, it shows regional differences.https://en.wikipedia.org/wiki/Akahoya_eruption
The Impact of Volcanic Eruptions on Human Society from an Archaeological Perspective
https://www.jstage.jst.go.jp/article/jaqua1957/30/5/30_5_427/_article/-char/en
https://en.wikipedia.org/wiki/J%C5%8Dmon_period
Added to timeline:
Date:
jan 1, 4350 BC
jan 1, 4300 BC
~ 50 years