Earth Planets Space, Vol. 54 (No. 3), pp. 211-216, 2002
Geological Survey of Japan, AIST, Central 7, Higashi 1-1-1, Tsukuba, Ibaraki 305-8567, Japan
(Received April 6, 2000; Revised August 30, 2001; Accepted October 6, 2001)
Abstract: A series of heat discharges from the Iwodake volcano was estimated using nighttime Landsat TM data. The data includes heat discharge only from steaming ground and excludes fumarole, hot spring activities and others. The heat discharge was estimated at 40-80 MW from 1989 to 1993 using temperature distributions derived from Landsat TM band 6, and started to increase since 1995. From the error analysis, the true heat discharge will be in the range from -60% to +20% of the calculated discharge of this method. Two hot spots in the northeast to southwest direction correspond to the high temperature fumaroles seen in the temperature distributions derived from band 7. A new hot spot corresponds to a new degassing vent has been observed on the southern end of the summit crater since January 1992, and expanded to the same size as the other two hot spots since December 1993.