Assistant Professor at University of Central Florida
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To further investigate the extraordinary mobility of rock avalanches, I employed the discrete element method to simulate the entire process of an earthquake-induced landslide (landslide initiation, propagation, and deposition). Through the case study, I observed that the progressive rock fragmentations and violent interparticle collisions significantly contributed to the extraordinary high mobility.
Early detection of rockslides at high-elevation and well-vegetated slopes remains challenging. This study used satellite and unmanned aerial vehicle (UAV) optical remote-sensing (ORS) images to track evidence of slope deformation and examine potential geomorphological precursors of five large rockslides in China. All the surveyed landslides had cracks or scarps and rockfalls within the landslide source area before the onset of rapid sliding. These precursors can be identified in ORS images taken several years or decades before the rapid slope failure, which provides sufficient time for the landslide early detection in practice. Local topography affects the spatial locations of cracks or scarps. Rockfalls within the landslide source area tend to locate at “key blocks” where slope mass provides forces resisting sliding. The rockfall area ratio, defined as the accumulated area of rockfalls over the landslide source area, ranged from 0.33 to 0.92 before rapid slope failure. The landslides developed on anti-dip and igneous rock slopes show a more significant rise of rockfall area ratio before the slope failure than the landslides on dip slopes. Given the broad availability of ORS data, this study could shed light on the ORS- based landslide early detection and landslide kinematics study.
The 2008 Ms 8.0 Wenchuan earthquake triggered more than 200 thousand landslides, including hundreds of catastrophic deep-seated rockslides. The Among these catastrophic rockslides, the Daguangbao (DGB) landslide is the largest landslide triggered by the Wenchuan earthquake (28°38′16.93′′ E, 104°06′02.35′′ N). The DGB landslide moved the slope mass with volume of 1.2 billion cubic meters to covered an area of 7.8 km2, and formed a landslide dam nearly 600 m high. We had done detailed geological, geophysical, and geotechnical surveys to study the failure mechanism of this giant landslide. I observed that a 3-meter-thick fault gouge was well extended along the sliding bed and with a maximum burial depth of ~400 m. Geotechnical laboratory experiment results suggested that the weakest sublayer within the fault gouge consists of silt soils with strain hardening and liquefaction behaviors. I concluded that slippery fault gouge and strong earthquake-induced shaking led to the giant landslide.
Landslide inventory plays an important role in regional landslide susceptibility assessment and uncovering landslide formation mechanisms. I studied the remote-sensing-based landslide mapping and landslide inventory development for earthquake-impacted areas following strong earthquakes. I conducted statistical analyses to investigate the spatial distribution pattern of coseismic landslides with respect to different seismic, terrain, and geological factors. In this setting, I found high landslide density at lower slope sections where the landform evolves from upper, broad valleys to lower, deep-cut gorges. The spatial distribution of the coseismic landslides did not seem correlated to the location of any known active faults. In contrast, I revealed that a previously unknown blind fault segment is the plausible seismogenic fault given the characteristic landslide density break across that fault line.