- Japan was originally part of Asia, but as the Philippine Plate subducted beneath the continental Asian Plate and the Pacific Plate subducted beneath Japan, Japan was pulled eastward as the back-arc extended and the Sea of Japan was formed. This rifting of a continental margin continued and there was a trench triple junction to the east of Japan that further affected tectonic instability.
- A long volcanic arc the length of the 6000# islands was the result of several periods of magmatism from the initial back-arc opening with a felsic caldera-forming phase evolving into a dominantly andesitic stratovolcano phase. The country is ~71% mountainous terrain.
- Japan has 120# Holocene volcanoes that mostly originated above the mantle wedge in the subduction zone. ~111# are considered active. There have been ~130# significant eruptions over recent history.
- Japanese geothermal power has been developed for some time, but significant potential remains. There are 18# geothermal power sites currently, but ~60# additional sites are being considered.
