Interaction of earthquake-triggered landslides and local relief: Evidence from the 2008 Wenchuan earthquake

Earthquake-triggered landslides (EQTLs) are affected by both seismogenic faults and topography. Using landslide data associated with the 2008 M(W)7.9 Wenchuan earthquake, the distribution characteristics of EQTLs were identified. And the influence of topographical changes and fault dip angle changes on the distribution of EQTLs was analyzed. Fault dip angle had a controlling impact on EQTL spatial distribution. When the dip angle increased, EQTL distribution was concentrated in a certain range on both sides of the fault and decayed rapidly with distance from the fault. When dip angle decreased, the hanging wall effect became more obvious, and the number of landslides on the hanging wall gradually decreased with distance from the fault. In terms of topography, EQTLs were closely related to relative elevation differences, forming a single peak for a local relief range of 400-1600 m. For > 70% of statistical units, EQTL density increased with local relief; the landslide distribution conformed to an exponential relationship with relief. Peak local relief and dominant local relief were highly negatively correlated with fault dip angle. Fault geometry and motion characteristics control the propagation of seismic waves, directly affecting the distribution of EQTLs; moreover, as tectonic activity controls local relief, it also indirectly affects the distribution of EQTLs. Our findings provide empirical evidence for the rapid assessment of EQTL distributions.

Automated summary

Earthquake-triggered landslides are influenced by both seismogenic faults and topography. The dip angle of the fault has a controlling impact on the spatial distribution of the landslides. Higher dip angles result in a concentrated distribution of landslides on both sides of the fault, while lower dip angles lead to a more pronounced hanging wall effect. The topography, particularly the relative elevation differences, is closely related to the landslides, forming a single peak within a local relief range of 400-1600 m.