Continuous monitoring of fumarolic gas flux at a bore hole in an active volcanic island

A new method for continuous monitoring of fumarolic gas flux at a bore hole is here described. We measured the vertical temperature distribution conti nuously using a DTS (Distributed Temperature Sensor) system in a volcanic i sland, Izu-Oshima, central Japan. The vertical temperature profile is expre ssed as a function of gas flux. We then obtain continuous data on relative gas flux with a time interval of one hour. The gas flux appears to fluctuat e in response to atmospheric pressure changes, and we support that the char acteristic response of the gas flux can well be simulated using a pore pres sure diffusion model. This method will be useful to detect changes, even sm all, in the fumarolic gas flux related to volcanic activity.