Estimation of heat discharge rates using infrared measurements by a helicopter-borne thermocamera over the geothermal areas Unzen volcano, Japan

Unzen volcano is situated on Shimabara Peninsula, western Kyushu, Japan. On the flank of the volcano, the Obama, Unzen and Shimabara hot springs are aligned in a direction from the southwest to the northeast across the peak. At Obama and Shimabara, heat is transferred mainly by water flow. But at Unzen heat is transferred by the discharge of natural steam and by conduction as well as water flow. In order to estimate the heat discharge by mechanism other than water flow, infrared measurements by a helicopterborne thermocamera were conducted over the Unzen hot spring area. The heat discharge was calculated from the thermal image by a method based on heat balance of the ground surface resulting in a value of 1.9 x 106 cal/s (7.9 MW). (orig./ME)