鳥海山北麓における地震探査, 電磁探査法の総合解析例

抄録

We present a comparison between the 2-D resistivity structural model (EM model) and the structural model derived from the seismic survey (seismic model) in the northern slope of Mt. Chokai.
From 1989 to 1991, three types of electromagnetic survey and two types of resistivity survey were conducted along the seismic survey line that was acquired by JNOC in 1985.
EM model was constructed from electromagnetic and resistivity survey data by using some inversion and forward modeling techniques. The well data (MITI Nikaho) and another electromagnetic data collected near by the well were used to the geological interpretation.
Seismic model was derived by using inverse ray method (May and Covey, 1981). In this method, 2-D depth model is computed from reflection times of interpreted horizons on CDP-stacked section and spatial velocity function.
As a result of the comparison, these models are not consistent in the deeper part, while they agree quite well in the shallower part. The uniqueness of the 2-D resistivity structural model was examined through some model calculations. Other possible explanations concerning the difference of these models are also discussed in this paper.