東北日本における火山フロントと稍深発地震活動

概要

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Having investigated spatial variation of seismicity in the Pacific slab beneath northeastern Japan using JMA data since 1995, we found that number of earthquakes in the upper seismic plane decreases remarkably near the volcanic front and on its deeper side. The change in the seismicity is so clear that we can separate the active and inactive areas by a line. We show that the boundary line in the seismicity in the upper seismic plane delineates eastern boundary of the distribution of volcanoes and it runs almost parallel to the Volcanic Front. Further, a remarkable correspondence is observed between the boundary line and an active belt of shallow inland seismicity in northeastern Japan. In lwate Prefecture where the active seismic belt bends to the west the boundary line is curved to the west as well. We think the conspicuous decrease of the seismicity in the upper seismic plane beneath the volcanic front and on the deeper side is causally related to the formation of magma bodies along the subduction zone.
特定非営利活動法人日本火山学会の論文
2002-01-15