Landslide erosion associated with the Wenchuan earthquake in the Minjiang River watershed: Implication for landscape evolution of the Longmen Shan, eastern Tibetan Plateau

In tectonically active mountain belts, earthquakes can contribute to surface erosion by generating large-scale landslides. This study focuses on establishing the relationship between surface erosion caused by the earthquake-induced landslides and landscape evolution of the Longmen Shan, eastern Tibet Plateau. The inventory of landslides related to the 2008 Wenchuan earthquake in the Minjiang River watershed was based on high-resolution remote sensing images and field surveys. The estimated landslide erosion rate related to the Wenchuan earthquake is of the order 0.4–0.6 mm year−1 on both sides of the Minjiang River and its tributaries. This erosion is similar to erosion rates of 0.5–0.8 mm year−1 measured by low-temperature thermochronology over a Myr-timescale. The landslides associated with repeated large earthquakes may contribute to this Myr-timescale surface erosion via enhanced erosion efficiency. Post-seismic high-resolution digital elevation models covering the period from 2008 and 2012 were compared to quantify fluvial erosion in the Baisha River, a tributary of the Minjiang River. The volume of eroded materials was approximately 1.9 × 104 m3 over the 4-year period. In addition, the rapid removal of co-seismic knickpoints indicates significant post-seismic river transportation. If large earthquakes, such as the Wenchuan earthquake, have occurred at intervals of 2,000–3,000 years, then the associated rapid landslide erosion together with fluvial erosion during inter-seismic intervals may have played an important role in shaping the present landscape of the Longmen Shan.