Gravity and magnetic surveys have been carried out in the Tatun volcanic field in order to analyze the subsurface structures, the extension of the Chinshan Fault and the volcanic rock distribution in the surveyed area. Qualitative interpretation of gravity data indicates that the highest gravity zones are located in the Hengshantsun, Chihsingshan, Tatunshan, Matengshan, and Chutzushan regions, whereas the lowest gravity anomaly is in the Yukuangkengt'ou region.
The inverted density/depth models are comparable to the surface geo­logic characteristics. The density discontinuous zones are related to the Chin­-shan fault. The magnetic high anomalous areas, such as the Hengshantsun, Tatunshan, Chutzushan, Hsiaokuanyinshan, and Yangmingshan regions are also the gravity high regions except for the Chihsingshan regions which, how­ever, does show a low magnetic anomaly. Gravity and magnetic studies reveal comparable results. The geophysical anomalies support most of the major ge­ological features presented in the studied area.