Distribution and characteristics of loess landslides induced by the 1718 Tongwei earthquake based on a field survey

Based on a field survey, data on 724 loess seismic landslides induced by the 1718 Tongwei earthquake were acquired. The relationships between the landslide distribution, seismic intensity, epicentral distance, and original slope angle were analyzed to better understand the geometrical, directional, and kinematic characteristics of loess seismic landslides. The results indicate that (1) the seismic intensity and epicentral distance, which are essential factors controlling the spatial distribution of loess landslides induced by the 1718 Tongwei earthquake, are significantly correlated with the landslide scale. (2) The original slope angle of seismic landslides is generally moderate, and the dominant angle ranges from 10 to 25°. (3) The main sliding directions of the landslides are concentrated in the ranges of 30 to 40°, 180 to 190°, and 250 to 260°. The correlation between the main sliding direction of the landslides, the original slope aspect, and the relative epicenter azimuth demonstrates that the propagation direction of seismic waves and the original slope aspect influence the main sliding direction of landslides. (4) The equivalent friction coefficient (μ) of these landslides is between 0.07 and 0.67, with an average value of 0.25. The empirical relationships of kinematic characteristics suggest that these landslides are characterized by significant scaling effects, low slope angles, and long sliding distances. The findings of our study are worthy for use in engineering applications and will pave the way for additional studies into the mechanism and risk assessment of loess seismic landslides.