CEE SEMINAR: Time-varying Damping Ratios and Seismic Velocities in a High-Rise during Earthquakes from Coda Wave Interferometry

Abstract: Coda wave seismic interferometric techniques are applied to 2019 M7.1 Ridgecrest earthquake and ambient vibration wavefield data from an instrumented high-rise for time-varying damping ratios and seismic velocities. The data are from the Community Seismic Network consisting of low-cost accelerometers deployed at the ground level and on every upper story of several high-rises in Los Angeles. Narrowband damping ratios increase by up to a factor of 4, and velocities are reduced by up to 12% over short time durations spanning the main shock and M>4.5 aftershocks. The results demonstrate how this method could be used to detect small-scale damage.  

Bio: Monica Kohler’s research is focused on identifying and characterizing deformation and failure such as fractures due to earthquakes in civil structures through numerical and observational experiments. She is on the science leadership team of the Community Seismic Network project developed at Caltech, and has held research positions at Caltech and UCLA in civil engineering and seismology. Kohler received her doctorate in geophysics from Caltech and bachelor's degree from Harvard University.