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Mechanical and Civil Engineering Seminar

Thursday, April 30, 2020
11:00am to 12:00pm
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Online Event
Interaction of Seismic Waves with Geomaterial Heterogeneity: From Multi-Scale Scattering Mechanisms to Dynamic Response of Geostructures
Kami Mohammadi, Dr., Department of Mechanical and Civil Enineering, California Institute of Technology,

*Connection details for this online presentation will be posted when available.

The scattering of seismic waves due to geometric irregularity and material heterogeneity is a topic of interest in various fields of science and engineering. Examples of such scatterers include continental margins and crustal discontinuities in geophysics, ground surface topography and man-made earth structures in geotechnical engineering, and surface defects in non-destructive testing. There is a common mathematical problem behind all of these phenomena, which describes the scattering of incident wave by a feature, whose characteristic length is comparable to the dominant wavelength. In this seminar, I will present results from my study on the response of topographic features to seismic waves. Starting with a 2D infinite wedge in a homogeneous elastic medium, I will extend the state-of-the-art understanding of wave focusing and scattering by this fundamental block of ground surface irregularity up to a realistic 3D topographic feature. The theoretical results and their comparison with actual field observations provide new insight into the effects of surface topography and its nonlinear coupling with subsurface layering, which are frequently ignored in earthquake simulation and engineering design. Next, I will integrate the understanding of seismic wave scattering by surface irregularity with a hybrid continuum-discrete technique to model near-surface mechanical weakening. The results will be used to evaluate the natural and anthropogenic seismic events as a preparatory factor of slope failures like those in dams and embankments.

For more information, please contact Carolina Oseguera by phone at (626) 395-4271 or by email at [email protected].