Fig. 9

Close-up views of the profiles of the Bouguer anomaly (a) and the topography of the basement surface (b) around the Takahama Fault. The tip of the Takahama Fault is located at 22.98 km. a The observed and interpolated residual Bouguer anomalies are represented by open circles and the cyan line, respectively. The interpolated residual Bouguer anomalies come from that of the Fig. 3d. The green line and red line represent the calculated Bouguer anomaly from the initial model (green in b) and the optimum model (red in b) using the 2D Talwani’s method. b The green line represents the initial model extracted from the gravity basement model (Fig. 7) along the survey line. The red line represents the optimum basement model obtained by selecting the best parameters (Table 2). The black line represents the elevation of the ground surface. The origin of the x-axis is set at the tip of the Utsumi Fault in both a and b