Recovering Surface Slip Distribution Along the Sertengshan Piedmont Fault (Northern China) From Airborne LiDAR Data

Slip from paleoearthquakes is preserved in geomorphology in the form of displaced landforms. By recovering the surface slip distribution of displaced landforms along a fault, we can constrain the earthquake rupture histories and recurrence characteristics on the fault, thus benefiting seismic hazard assessment. In this study, 1-m-resolution airborne Light Detection and Ranging data were obtained along about 185 km of the Sertengshan Piedmont Fault, which is a dip-slip normal fault located at the northern margin of the Hetao Graben around the Ordos Block in Northern China. A total of 601 vertical displacements were measured on different geomorphic surfaces along the fault strike. Through statistical analysis of the displacement measurements, it is inferred that at least five to seven large earthquakes have ruptured this fault, displaying a remarkably regular slip increment of similar to 2 m. Compared with the slip, the recurrence intervals of paleoearthquakes exposed by previous paleoseismic excavations are less regular, which may be due to the different recording capacity of geomorphic and paleoseismic markers. By recovering the surface slip distributions of several recent events, we identified several large full-rupture earthquakes that may have broken two adjacent segments together and smaller partial-rupture events that have ruptured only a part of the segment, thus suggesting a bimodal rupture behavior for the fault. Our estimates indicate that rupturing of the Sertengshan Piedmont Fault may yield a large earthquake of M-w 7.1-7.5, leading to significant seismic hazards in the densely populated Hetao Graben area.