Assistant Professor Eric Kiser is part of a NASA NSPIRES program grant: "Large landslides and landslide/glacier-dammed Himalayan and Karakoram rivers and the potential for transboundary disruptions." Kiser is working with Jeffrey Kargel, Research Scientist with UA Department of Hydrology and Atmospheric Sciences, and Umesh Haritashya of the University of Dayton to investigate geologic and topographic settings and triggers of large historic, pre-historic, and future landslides in the Himalaya and Karakoram mountain ranges.
Here, Kiser describes the project:
Earthquakes, along with monsoon rains and ice flow, frequently trigger large and fatal landslides and avalanches in the High Asia region (Figure 1). In addition, the rapid retreat of glaciers in this region creates large lakes contained by loose moraine deposits that are susceptible to failure due the stress perturbations associated with seismic waves. Our project seeks to investigate geologic and topographic settings and triggers of large historic, pre-historic, and future landslides in the Himalaya and Karakoram mountain ranges, including river damming and other associated hazardous events with transboundary consequences. This work will combine satellite- and field-based data, modeled terrain susceptibilities for large landslides, and seismic wavefield simulations. Initial efforts will focus on the 2015 Gorkha earthquake (Figure 2) and the 2005 Kashmir earthquake.
In order to understand the relationship between the properties of earthquake sources, regional geologic structures, topography, ground motion, and landslides, we will use SPECFEM3D and the meshing software Trelis to model wavefield propagation associated with large earthquakes and their aftershocks. Earthquake scenarios
that may be relevant for future events will also be explored, including in regions adjacent to the 2015 Gorkha earthquake. All simulations will incorporate local geologic features including the Pokhara- Gorkha anticline, the Kathmandu basin, and abrupt changes in rock types associated with the various thrust faults in the region (e.g., Lavé and Avouac, 2000). In addition, high-resolution DEM will be used to accurately represent topography. Ground motion parameters such as peak ground velocity and acceleration, shaking duration, and wavefield backazimuth and incidence angle will all be calculated from these simulations and compared with landslide data and modeled landslide susceptibilities. Figure 3 shows an example of a wavefield simulation from a thrust-faulting event over complex Himalayan terrain. Comparing this simulation with one in which there is no topography illustrates the local amplification of ground motion near ridges.