Remote sensing of high temperature on the slope of Mt. Unzen-Fugendake volcano by infrared thermometer

A remote sensing method was applied for estimating temperatures on the slope of Unzen-Fugendake volcano by a visual type infrared thermometer. The maximum values of surface temperatures on the northeast slope were 195/spl deg/C on 18 October 1991, 138/spl deg/C on 13 March 1992 and 134/spl deg/C on 22 January 1993. The surface areas of elevated temperature (>50/spl deg/C) were estimated to be 149000 m/sup 2/ on 18 October 1991 and 99000 m/sup 2/ on 22 January 1993. The maximum values of surface temperatures on the east slope were 131/spl deg/C on 18 October 1991, 215/spl deg/C on 13 March 1992 and 185/spl deg/C on 22 January 1993. The surface area of elevated temperature (>100/spl deg/C) were estimated to be 956000 m/sup 2/ on 8 January 1992, 632000 m/sup 2/ on 3 April 1992 and 62000 m/sup 2/ on 22 January 1993. The high temperature area (>1OO/spl deg/C) expanded rapidly due to pyroclastic flows. The decreasing rate of surface temperatures of pyroclastic flow were 3.9/spl deg/C/min in the period of 2/spl sim/12 minutes after the pyroclastic flow and 2.4/spl deg/C/min in the period of 17-24 minutes.<
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