MT study in Chingshui geothermal area of Taiwan

Han-Lun, Hsu

Abstract

The Chingshui geothermal area in Yilan has ever been developed as a geothermal power plant in Taiwan, 1981. The power station was stopped operation because the water pipe had been blocked seriously and the hot water and steam reduced greatly. We did MT survey in order to understand whether there is potential geothermal energy in depth. For deep investigation, we used the magnetotelluric (MT) method that could analyze the deep structure more than 1 km.

To increase the signal to noise ratio, besides following the traditional MT data collection, we have tested to record MT data by prolonging time as long as three days and we also use the remote-reference for improving the quality of data. The results show that three days record and remote-reference are needed for high quality MT data acquisition in Taiwan area. Then we use the Groom and Bailey decomposition analysis (GB decomposition) for the geoelectric strike determinations.

The result of MT study in Chingshui area shows the relation between geothermal source and low resistivity structure. We can suggest that the heat source comes from the south of the region and its depth is about 8 km. The hot spring could be the meteoric water which permeated into deep strata and was heated by geothermal source and then appeared on the earth’s surface along the fracture of strata. Thus, the Chingshui geothermal area is high potential for power plant. Lastly, we also find a deeper heat source that down to the depth of 20 km which is perhaps due to the collision of plates in Taiwan area.