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Aerial IR surveys were carried out in September 2010 over geothermal areas at Usu,Noboribetsu and Hokkaido-Komagatake volcanoes, Japan. The heat discharge rate from steaminggrounds that formed during the 2000 eruption of Usu volcano is estimated to be 5.6 MW, whichis half the rate measured in September 2006. Integration of the heat discharge rate from April2000 to September 2010 yields an accumulated discharge of approximately 2.4 × 1016 J. This amount of heat corresponds to several percent of the total intruded magma heat estimated fromanalyses of ground deformation associated with the 2000 eruption. Areas of steaming groundassociated with the 2000 eruption showed rapid growth compared with those of the 1977 eruptionbut discharged less heat. We suspect that differences in the hydrological environments of thetwo eruptions, led to contrasting patterns of propagation of the hydrothermal systems around theintruded magmas. The heat discharge rate from the summit areas of Usu volcano, Showa-shinzan andNoboribetsu volcano in 2010 are estimated to be 40, 6.2 and 22 MW, respectively, similar to therates measured in September 2006. No high-temperature grounds were detected at the vents and fissure formed during the1942 eruption of Hokkaido-Komagatake volcano. We observed no geothermal activities at ventsassociated with the 1929, 1996, 1998 and 2000 eruptions, due to the absorption effect ofatmospheric cloud.
北海道大学地球物理学研究報告 (75), 25-41, 2012-03-00