(By T. Miyazaki, 2010)

Japan is a part of the Eurasia continent and made up of more than 6,000 islands.  Also, it is fomed on the volcanic line, called "Ring of Fire."  Many scientists believe that most of Japan Islands were under the sea before Miocene. (1)  Lifting Japan islands started in the early Miocene by volcanic activities that was related to the shift trenches of the Pacific, Eurasia, and Philippine plates.  In the late Miocene, the current Japan Islands were formed by shifting volcanic-arcs from the back-arc to the front –arc when the trenches moved back the trenches.  Also, most volcanoes which created the formation of the current Japan Islands exhausted, and they disappeared in the early Miocene that they left scars of their activities on the surface.   Most current volcanoes have been active since Holocene and have mainly formed stratovolcano.  Some active volcanoes have been studied to understand the intensiveness and scale of volcanic hazards from thier eruptions.  Moreover, the volcanic hazards in Japan are very similar to the hazards of the Cascade volcanoes in the United States because both volcanic activities are linked together by the "Ring of Fire."


ring of fire


(1)   Takeyoshi, Yoshida.  "Tertiary Ishizuchi Cauldron, Southwestern Japan Arc: Formation by Ring Fracture Subsidence." 

            Journal of Geophysical Research, Vol. 89, No. B10, Pages 8502-8510, September 30, 1984.

(2) USGS.  "Active Volcanoes and Plate Tectonics "Hot Spots" and the "Ring of Fire."  January 2, 2003. <http://vulcan.wr.usgs.gov/Glossary/PlateTectonic /Maps/map_plate_tectonics_world.html>