Modeling the Combined Effects of Deterministic and Statistical Structure for Optimization of Regional Monitoring
Final rept. 4-30 Jun 2015
CONNECTICUT UNIV STORRS DEPT OF PHYSICS
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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 equilibrate 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 in the region of the Lop Nor test site. This is accomplished by synthesizing seismograms using a radiative transport technique to predict the high frequency coda 2 to 4 Hz of regional seismic phases at stations having known large-scale threedimensional structure, combined with experiments to estimate the effects of multiple-scattering from unknown small-scale structure. We describe a code to shoot body wave rays through general deterministic 3-D structure, including the coda envelope sensitivities to parameters describing the heterogeneity spectrum, intrinsic attenuation, Moho transition, and tectonic release of nuclear tests. We predict that discriminants in this region based on PLg amplitude ratios will best separate earthquake and explosion populations at frequencies 2 Hz and higher.
- Radiofrequency Wave Propagation