Detection of lithological regulation on coseismic landslide depths using detrital 10Be dilution

• A nuclide dilution model was applied to evaluate the coseismic landslide geometry regulated by lithology. • Landslide area–volume scaling parameters were calibrated for each lithology area damaged by the 2008 Wenchuan earthquake. • Rock mass features control contrasting landslide depths. In this study, the feasibility of using the dilution concept of cosmogenic nuclides in fluvial sediment to quantify the coseismic landslide depths regulated by the lithological conditions of hillslopes was demonstrated. The model was applied to mountainous watersheds underlain by granitoids and phyllite subjected to extensive bedrock landslides during the 2008 Wenchuan earthquake. On the basis of the compiled datasets of postevent detrital 10 Be concentrations and a thorough landslide inventory, the landslide area–volume scaling parameters were calibrated for each lithology. The optimal parameter values indicated that the landslides tended to be shallower in massive granitoids than in phyllites, in which highly discontinuous bedrock caused deep-seated landslides. These results support the feasibility of nuclide dilution modeling in landslide studies.