The Izu Peninsula Geopark for beginners: a volcanic island that crashed into Japan
How a chain of undersea volcanoes drifted north and joined Honshu, and where to see the evidence on the ground.
The whole Izu Peninsula is a UNESCO Global Geopark, designated in 2018. Its theme is "volcanic gifts from the south", and its story is unusual even by Japanese standards.
The short version
- Millions of years ago, Izu was a group of undersea volcanoes far to the south, riding on the Philippine Sea plate.
- The plate carried them north until they collided with Honshu, roughly 1 million to 600,000 years ago depending on the study, and joined the mainland as a peninsula.
- Large land volcanoes such as Amagi then grew on top, and a field of small volcanoes, the Higashi-Izu group, still erupts from time to time. Mount Omuro was formed by one of them.
Where to see it
- Ryugu Sea Cave and the white cliffs of south Izu: undersea volcanic deposits lifted out of the sea.
- Jogasaki coast: lava from Mount Omuro cut by the waves.
- Mount Omuro: a young scoria cone you can walk around.
- Kawazu Seven Waterfalls: falls flowing over lava.
The geopark has visitor centres around the peninsula; guided walks can be booked in English on some routes.
