| Summary: | 碩士 === 國立臺灣大學 === 海洋研究所 === 97 === This study was supported by the Central Geological Survey. We analyzed 3 thermal research boreholes at Chinshan, Chuhihu and Chinteinguan located in Tatun volcanic area. The depths of the boreholes are about 200~480 m and the diameters of the holes are around 13 cm. In order to monitor the long-term ground temperature variation of Tatun volcano and to investigate the possibility of volcanism in Tatun volcanic area in the future, we installed a string of the miniature probes in each borehole.
As a result of the rock property and the structure of cement between sleeves and rocks at Chinshan station, the down hole temperature variation at the depth of 20~110 m is about 0.446~1.984 ℃ affected by the rain, and below 110 m is about 0.061~0.924 ℃. The temperature below 130 m decreased continuously with respect to time for the previous two years.
The temperature at Chuhihu station is relatively stable. As a result of the cool groundwater at 88 m and at 138 m, the temperature gradient is negative. The heat flow is about 192.4 mW/m2 between 88 m and 118 m. We believe that the heat has leaked when passing upward.
Chinteinguan is a geothermal active area. The temperature increased continuously for the previous 15 months. The increasing rate(0.64 ℃/year) and amplitude(0.78 ℃/15months) is considerable. Perhaps, it’s too early at this stage to propose that the magma under the Tatun volcanic area is rising, because data recordings are not long enough. We are sure more interesting volcanic signal may come out in the future at Chinteinguan station.
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