High Frequency Ground Motion High-Simulation Using a Source- and Site-Specific Empirical Green’s Function Approach

Abstract

A key limitation of seismic wave propagation simulations is that the seismic wave-speed structure of the earth is not well resolved for propagating high-frequency waves. The high frequencies in the ground motion must be simulated through other means. Toward this end, we adopt the classical empirical Green's function (EGF) approach of summing recorded seismograms from past small earthquakes with suitable time-shifts to generate seismograms for large events. Whereas, in the past, the magnitude of events used as EGFs were limited to within 1 or 2 units of the target event’s magnitude, this source- and site-specific approach allows us to use vast number of seismograms from very small earthquakes (magnitudes 2.5-3.5) as EGFs to produce the high-frequency content of large earthquakes. We are expanding the envelope of the empirical Green’s functions approach by using large number of seismograms from small earthquakes as EGFs to produce high frequency content of large earthquakes.