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Geomechanical Modeling of Ground Surface Deformation Associated With Thrust and Reverse Fault Earthquakes

We seek to improve our physical understanding of the factors that control the style, distribution, and intensity of ground surface ruptures on thrust and reverse faults during large earthquakes. Our study combines insights from the patterns of coseismic ground surface rupture from historic earthquakes and paleoseismic studies to inform the development of a suite of geomechanical models using the discrete element method (DEM). We explore how various parameters, such as fault geometry and sediment/soil properties, control ground deformation patterns including scarp dip, width, and patterns of secondary folding and fracturing. The DEM method is well suited to this investigation as it can effectively model the geologic processes of faulting and folding at depth, as well as the granular mechanics of soil and sediment deformation in the shallow subsurface. The method can also directly represent surface and subsurface infrastructure in rupture models, to explore how various patterns of ground surface deformation may impact the built environment. We present an initial suite of models to illustrate characteristic patterns of ground surface deformation and show how these vary as a function of sediment/soil properties, fault dip, and other factors. Our initial results show that localized fault scarps are most prominent in cases with homogenous sediment strength and steeply dipping faults, whereas broader fold scraps are more prominent with vertical gradients in sediment strength and shallowly dipping faults.

Presenting Author: Kristen Chiama

Student Presenter: Yes

Day: 4/23/2021

Time: 9:45 AM - 11:00 AM Pacific

Additional Authors