Abstract
Supercritical geothermal fluids, which was mostly derived from the lower crust and upper mantle, could be evaluated in terms of present volcanic activities. Magmatic processes ongoing during the formation of the caldera itself provide significant geological evidence for water budget into the Earth’s crust. With an assumption that such amount of water supplied to the magma chamber continuously during certain periods of time, the average water input to the crust supplied by the subducting slab is estimated to be 10-20 (average 15) ton/year/meter arc length.