Fig. 1

Study area. a Overview of topographic map (contour interval of 10 m, provided by Geospatial Authority of Japan) showing the location of study area. b Orthorectified aerial photograph of the study area (taken on December 2014). The target zone of TLS measurement (50 m × 60 m) is shown by a white dashed line. c Masked target area for the analyses. A–A′ to C–C′ indicates locations of topographic section lines shown in Fig. 5. Numbers associated with vertical (N–S) and horizontal (E–W) thin lines indicate grid coordinates on UTM Zone 54N (JGD2000 datum) projection