3. Aeromagnetic Anomaly and gravity Anomaly over and around Akita-Komaga-take(II. The Make-up of Akita-Komagatake)

Abstract

Aeromagnetic survey and gravimetric survey were performed over and around Akita-Komaga-take. Positive magnetic anomalies caused by each volcanic cone of Akita-Komaga-take, Eboshi-dake and Takakura-san were observed. Zarumori-san did not create an appreciable magnetic anomaly. Near Me-dake a small magnetic anomaly of negative sense was observed, and it surely concerned to the eruption of 1970. The existence of thermal material concerning this negative anomaly was estimated. From gravimetric data Akita-Komagatake is located in the central area of a positive anomaly which is related to irruptive rocks. In the western side of Akita-Komagatake weak negative magnetic anomaly was observed. It corresponds to negative gravity anomaly in northeastern side of Tazawa lake. These anomalies do not correspond to surface geology, so these may show influence of subterranean structure.