大屯火山群位於台灣北部，根據分析噴氣之氦同位素顯示，部分噴氣來自岩漿源，說明台灣北部地下有岩漿庫存在之可能，從地震分佈與震源特性，亦顯示七星山及大油坑附近有明顯的微震活動存在，初步推斷此地區之微震可能是岩層裂縫中液態或氣態物質之震動所造成，這些現象與國外其他火山地區所觀測之岩漿相關活動類似，再由電性構造亦顯示，七星山及大油坑附近之上部地殼中所觀測到電性地層分佈，在地下約6 Km深處，發現一近似球狀構造，可能與岩漿庫有關(圖1)，從台灣北部因大屯火山群位於台灣北部，根據分析噴氣之氦同位素顯示，部分噴氣來自岩漿源，說明台灣北部地下有岩漿庫存在之可能，從地震分佈與震源特性，亦顯示七星山及大油坑附近有明顯的微震活動存在，初步推斷此地區之微震可能是岩層裂縫中液態或氣態物質之震動所造成，這些現象與國外其他火山地區所觀測之岩漿相關活動類似，再由電性構造亦顯示，七星山及大油坑附近之上部地殼中所觀測到電性地層分佈，在地下約6 Km深處，發現一近似球狀構造，可能與岩漿庫有關(圖1)，從台灣北部因碰撞作用所生成的造山崩解張裂活動亦逐步加強發育當中，張裂活動隨時有可能提供充分管道給岩漿噴發至地表，因此大屯火山地區進一步仔細探查，確認岩漿庫存在之真實性有其必要。本研究計畫以一年的時間於七星山地區利用深部電磁測勘技術設置8個不等之大地電磁法觀測站，以瞭解本地區深部50km內是否岩漿庫存在之可能。工作項目主要包括測區地熱文獻收集，研判出重點施測範圍、補行關鍵位置測勘、資料處理、分析電性構造、解釋深部火山構造，再配合地質資料、地溫資料、微震觀測及地表地殼變形等資料上約制，以建構完整的地熱概念模式，辨認大屯山地區火山岩漿存在及活動範圍。我們有此信心是因為TAIGER深部(50km)電探之成功以及台灣全島三處大地電磁遠距參考站已建立完成，可配合施測，可達到高解析度深部電性資料之解析。 The Tatun volcano group is located at the northern tip of Taiwan. Based on the geochemical analysis from fumarole gas shows that the Helium isotope ratios are very high and strongly indicate that some magma chambers might still exist beneath the Tatun volcano group area. The seismic array recorded several volcanoseismic signals, that have often been reported in active volcanoes worldwide. In addition, the resistivity section also indicated a dome structure at depth around 6 km that is closely related to the structure of magma chamber (Figure 1). Combining the earthquake activity and the resistivity section along with the previous analysis of Helium isotope ratios, we suggest that it should be further investigated whether the magmatic plumbing system beneath the Tatun volcano group is still working. It is thus proposed to detect the possible location of the magma chamber in Tatun vocano group geothermal areas by using the deep electromagnetic soundings. Magnetotellurics (MT) will be carried out in this area. The geothermal structures may be evaluated in details based on the geoelectric data collected by MT observations incorporated with known geologic, seismic, and the known related data. The geothermal model, especially the heat source of the magma chamber and the related parameters of the reservoir will be obtained. With the help of three continuous remote reference sits around Taiwan and the experiences gained after TAIGER project, we believe that the highest resolution of MT data could be collected and analyzed. 研究期間：9908 ~ 10007the help of three continuous remote reference sits around Taiwan and the experiences gained after TAIGER project, we believe that the highest resolution of MT data could be collected and analyzed. 研究期間：9908 ~ 10007
