Abstract
We synthesized information from recent high-resolution tomographic studies of large crustal earthquakes which occurred in the Japanese Islands during 1995-2008. Prominent anomalies of low-velocity and high Poisson's ratio are revealed in the crust and uppermost mantle beneath the mainshock hypocenters, which may reflect arc magma and fluids that are produced by a combination of subducting slab dehydration and corner flow in the mantle wedge. Distribution of 164 crustal earthquakes (M 5.7-8.0) that occurred in Japan during 1885-2008 also shows a correlation with the distribution of low-velocity zones in the crust and uppermost mantle. A qualitative model is proposed to explain the geophysical observations recorded so far in Japan. We consider that the nucleation of a large earthquake is not entirely a mechanical process, but is closely related to the subduction dynamics and physical and chemical properties of materials in the crust and upper mantle; in particular, the arc magma and fluids.
Original language | English |
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Pages (from-to) | 4-16 |
Number of pages | 13 |
Journal | Island Arc |
Volume | 19 |
Issue number | 1 |
DOIs | |
Publication status | Published - 2010 Mar 1 |
Keywords
- Arc magma
- Fluids
- Large earthquakes
- Mantle wedge
- Seismic tomography
- Slab dehydration
ASJC Scopus subject areas
- Geology