著者

伊藤 谷生 岩崎 貴哉

出版者

東京大学地震研究所

雑誌

東京大学地震研究所彙報 (ISSN:00408972)

巻号頁・発行日

vol.77, no.2, pp.87-96, 2002-12-27

---

In Japanese islands, there exist two ongoing arc-arc collision zones (Hidaka region in Hokkaido and Izu region in Honshu). This paper presents an overview for recent geophysical and geological researches on the arc-arc collisions. In the Hidaka collision zone, the Kuril forearc has been collided onto the Northeast Japan arc since Miocene. A series of intensive seismic reflection and refraction since 1994 provided clear images on the collision style including the crustal delamination of the Kuril forearc in this region. These results constrain an important process for the formation of continental crust. Namely, delaminated lower (more mafic) crust of the Kuril forearc is descending down, and being transferred into the mantle by the plate subduction. The resultant crust becomes more felsic, which probably will be a core of the continental crust. The deep structure and deformation style of the Izu collision zone, where the Izu-Bonin arc is colliding to Honshu Island, has not been clarified as yet. In this paper, some of the recent geological and geophysical studies in these regions are introduced.