Abstract
On 8 August 2017 an earthquake (MS7.0) occurred within Jiuzhaigou County, Northern Aba Prefecture, Sichuan Province, China, triggering 4834 landslides with an individual area greater than 7.8 m2 over a more than 400 km2 region. Instead of correlating geological and topographic factors with the coseismic landslide distribution pattern, this study has attempted to reveal the control from seismic landslide susceptibility mapping, which relies on the calculation of critical acceleration values using a simplified Newmark block model. We calculated the average critical acceleration for each cell of the gridded study area (1 km×1 km), which represented the seismic landslide susceptibility of the cell. An index of the potential landslide area generation rate was defined, i.e., the possible landsliding area in each grid cell. In combination with PGA (peak ground acceleration) distribution, we calculated such indexes for each cell to predict the possible landslide hazard under seismic ground shaking. Results show that seismic landslide susceptibility plays an important role in determining the coseismic landslide pattern. The places with high seismic landslide susceptibility tends to host many landslides. Additionally, the areas with high potential landslide area generation rates have high real landslide occurrence rates, consistent with dominant small-medium scale landslides by this earthquake. This approach can aid assessment of seismic landslide hazards at a preliminary stage. Additionally, it forms a foundation for further research, such as the rapid evaluation of post-earthquake landslides and identifying highly impacted areas to help decision makers prioritize disaster relief efforts.
Highlights
Earthquake-triggered landslides in mountainous areas are one of the most common geologic hazards
Based on distributions of slope’s critical acceleration and PGA, we evaluated the coseismic landslide potential by analyzing the difference between the seismic landslide susceptibility of a particular slope and the peak ground acceleration at that site following the Ms7.0 Jiuzhaigou earthquake
Smaller critical accelerations signify slopes that are more likely to fail under seismic load, while blue colors indicate relatively stable slopes
Summary
Earthquake-triggered landslides in mountainous areas are one of the most common geologic hazards. The 2008 Wenchuan M7.9 earthquake created up to 828 barrier lakes [1], their breaches further worsening the consequences of landslides. If we can determine the location and severity of the landslides rapidly after a major earthquake, it will undoubtedly provide very useful help for the rescue arrangement after the event. To this end, what controls coseismic landslide distribution is an important issue to address
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