抄録
As an origin of volcanic activity, two independent processes seem to be important, though the situation is too complicated. 0ne is the segregation process-gathering scattered liquids from partial-melt zone. Although details are not known, permeabilty of the liquid magma through the partial-melt zone is the most important quantity in this proess. Another is the ascending prcess of the segregated magma from some part of the partialmelt zone to near surface. In this process is involved a cooling history of a magmatic body. As for the rough estimations of cooling effects on the the ascending maga, we take into accounts of convective as well as conductive heat transfer coupled with Stokesian ascent velocity. 0btained results indicate that a magmatic body of less than a few kilometers cannot ascend without suffering severe cooling.
