(a) 3He/4He ratios to distance from the Heunghae fault line. Samples at latitudes higher than P-12 are marked with red circles. (b) 3He/4He ratios to distance from the Namsong fault line, which is not prominent. (c) 3He/4He ratios to distance from closer fault lines between the Heunghae and Namsong fault lines. Samples closer to the Namsong fault than the Heunghae fault are marked with blue circles.