3D surface displacement and surface ruptures associated with the 2014 M_w 6.2 nagano earthquake using differential lidar

Detailed locations of surface ruptures and the distribution of deformation associated with large earthquakes offer insights to understand subsurface fault slip. We estimated the surface rupture traces and the distribution of near-fault offset during the 2014 Nagano earthquake in Japan (M_w 6.2) using pre- and postearthquake topographic data acquired by light detection and ranging (lidar) surveys. We conducted differential lidar (Dlidar) analysis based on the particle image velocimetry (PIV) method applied to the high-resolution 2013-2015 lidar dataset. The results show the 3D displacement (vertical and horizontal) due to the 2014 event and surface ruptures on the displacement map as clear contrast. The 2014 surface rupture zone is divided into the northern and the southern subsegments based on the surface offset distribution and geometry of the surface rupture. Moreover, we calculated the dip angles using the amount of vertical offset and horizontal contraction and estimated subsurface fault geometry of both subsegments. Furthermore, we detected broad (~1-2 km) horizontal contractions on the northern and southern extensions of surface ruptures, reflecting a deep part rupture. The surface rupture traces and vertical offset distribution from our analysis are consistent with the slip distribution from geodetic and seismological models; this fact ensures that the Dlidar analysis is useful for understanding the crustal movements in the future because of the increasing use of lidar data.