Advancing Ground Motion Directionality Characterization for Seismic Hazard and Risk Analysis
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Alan Poulos
USGS
- Date & Time
- Location
- Hybrid In-Person and Online seminar via Microsoft Teams
- Summary
Understanding and characterizing the variation of earthquake ground motion intensity with horizontal orientation, a phenomenon known as ground motion directionality, can lead to more accurate seismic hazard and risk analyses, especially for buildings with directional sensitivities. This talk discusses recent advancements in ground motion directionality research, emphasizing improvements in both empirical and simulation-based methods. First, ground motion directionality is analyzed statistically using a large database of recorded earthquake ground motions. Next, physical mechanisms driving seismic wave polarization are examined, revealing that directionality is influenced by the polarization of S-wave, which typically governs the intensity of ground motion at distances of engineering significance. The orientation dependence of probabilistic seismic hazard analysis is then quantified using physics-based simulations of the Los Angeles metropolitan area. Finally, the impact of directionality in urban seismic risk analysis, which is usually neglected, is quantified through a variance-based sensitivity analysis. The findings indicate that both seismic hazard and risk are affected by ground motion directionality, highlighting the importance of considering these effects in future studies.