Distribution of Earthquake-Triggered Landslides across Landscapes: Towards Understanding Erosional Agency and Cascading Hazards

Gen Li, & Josh West

Submitted August 14, 2017, SCEC Contribution #7679, 2017 SCEC Annual Meeting Poster #136

In mountainous regions, earthquake-triggered landslides are a critical geohazard, a major agent of erosion, and a powerful driver of the carbon cycle. How landslides distribute across landscapes provides key information for hazard management and for better understanding orogenic evolution and the cycling of carbon. In this contribution, we study the distribution of landslides caused by the 2008 Mw7.9 Wenchuan earthquake at the eastern margin of the Tibetan plateau in the context of a review of recent advances in understanding landslide spatial patterns. We have previously produced a Wenchuan landslide inventory by mapping landslides from remote images. Combining this landslide inventory map with analysis of digital topography, regional geology, and ground motion data, we explore the controlling factors of the Wenchuan-triggered landslides concerning seismological parameters, topography, and lithology. We study the locations of the Wenchuan landslides relative to river networks to evaluate how and to what extent landslide debris supplies sediment to rivers. We examine the aspects of landslides and discuss how the preferred facing directions of landslides reveal information about the characteristics of earthquake source, seismic ground motion, and rupture propagation. We evaluate the distribution of landslides from hillslope tops to bases and discuss the implications for hillslope morphology. Assuming the Wenchuan seismogenic fault was a linear energy source, we can successfully model the pattern of Wenchuan landslides adapting the functional form of the law of seismic wave attenuation which accounts for both geometric spreading and quality decay. In conjunction with models predicting total volumes of earthquake-triggered landslides, this approach has promise for predicting the magnitude and the pattern of landslides caused by earthquakes with known characteristics of the seismogenic faults and the seismotectonic settings.

Key Words
earthquake-triggered landslides, seismic hazards, topography, erosion

Citation
Li, G., & West, J. (2017, 08). Distribution of Earthquake-Triggered Landslides across Landscapes: Towards Understanding Erosional Agency and Cascading Hazards. Poster Presentation at 2017 SCEC Annual Meeting.


Related Projects & Working Groups
Earthquake Geology