Magmatic gas consisting of HCl, SO2 and steam etc. is discharged from an area of about 350mx600m in the fumarole area at the active volcano, Mt. Kuju-Iwoyama, Central Kyushu, Japan. The main purposes of this study are to measure the emission rate of fumarolic HCl and to estimate the magmatic steam flux from the fumarole area. The emission rate of HCl from the fumarole area was estimated by a new method developed under this study, which uses the Cl concentration of acid rain precipitated around the fumarole area. The estimated emission rates of HCl range from 3.0 to 8.7 ton/day in 1991 and 1992, which coincides with fluxes estimated by another method by Ehara et al. (1981) in the late 1970's (0.8∼8.7 ton/day). Based on the Cl concentration of high temperature fumarolic gas condensates from the fumarole area and the HCI emission rate, the magmatic steam flux was calculated to be 360∼1400 ton/day during the early 1990's.
Resistivities of many types of dried rocks sampled from drilling core have been measured at temperature ranging from 372K to b73K under oxidizing and inert atmosphere. The resistivities and dielectric constants have been measured by placing the cylindrical rock piece between two electrodes. The results obtained are as follows, 1) The resistivities of many types of rock decrease with increasing temperature. 2) The resistivity of each rock shows hysteresis. One of the reason is that magnetite in the rock transform into hematite and has been confirmed by X-ray diffraction and magnetization measurements. 3) The temporary increase in rock resistivity has been caused by the formation of the intermediate product γ-hematite from magnetite before they finally transform into a-hematite when heated under oxidizing atmosphere. 4) Using the resistivity data of ten samples measured in an inert atmosphere, an empirical equation as a function of temperature is derived to predict the resistivities of rock. 5) Based on the resistivity data of taconite, magnetite and quartz, the mineral composition of the rock is calculated. If the resistivities of different minerals and their composition are known, rough esti-mates of dried rock resistivities will be possible.