Modeling the Combined Effects of Deterministic and Statistical Structure for Optimization of Regional Monitoring
Technical Report,01 Jul 2013,30 Jun 2014
University of Connecticut Storrs United States
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The differences between earthquakes and explosions are largest in the highest recordable frequency band. In this band, scattering of elastic energy by small-scale heterogeneity less than a wavelength can equilibriate energy on components of motion and stabilize the behavior of the Lg wave trapped in the Earths crust. Larger-scale deterministic structure greater than a wavelength can still assume major control over the efficiency or blockage of the Lg and other regionallocal seismic waves. This project models the combined effects of the large-scale deterministic and the small scale statistical structure to invert for improved structural models and to evaluate the performance of yield estimators and discriminants at selected IMS monitoring stations in Eurasia. This is accomplished by synthesizing seismograms using a radiative transport technique to predict the high frequency coda 5 Hz of regional seismic phases at stations having known large-scale three-dimensional structure, combined with experiments to estimate the effects of multiple-scattering from unknown small-scale structure. We describe a code and preliminary tests to shoot body wave rays through general deterministic 3-D structure, including the computation of quantities required to synthesize high frequency body wave coda generated by small-scale, statistically described heterogeneity. Modifications in this period include 3-D interfaces with generalized dips and generalized 3-D reflection-transmission at the interfaces. Example regional waveform envelopes at 4 Hz are synthesized and discussed for an earthquake and explosion source in the Lop Nor region.