東京大学重力基準点の重力変化

抄録

The Mogi model is an important approach to the crustal uplift associated with volcanic activities on the basis of elastic deformation of a semi-infinite solid with a spherical cavity. The multiple Mogi model newly proposed in this paper is an approach to a dilatant expansion of the crust, in which many spherical microcracks lie scattered under the Gaussian distribution law of statistics. Theoretical considerations of the shape of the Matsushiro uplift suggest that a multiple Mogi process has most probably taken place in the swarm epicentral region. roundwater flow into microcracks has made pore pressure increasing during th period of uplift. After spring water flowing along the fissure zone, the mean depth of micro crack istribution has become shallower due to the upward expansion of the dilatant zone and then the horizontal length scale of the dilatant zone has become greater than the vertical scale.