Regional Wave Propagation Including Small-Scale Heterogeneities and Q(f)
Technical Report,01 May 2016,30 Apr 2019
San Diego State University San Diego United States
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High-frequency synthetics computed in the SALSA3D velocity model overpredict Rayleigh wave amplitudes by more than an order of magnitude while underpredicting coda amplitudes on the Korean Peninsula. However, ensemble 0-4 Hz FD simulations of regional wave propagation with addition of a von Karman distribution of small-scale heterogeneities with correlation lengths of 1 km, Hurst number of 0.1, horizontal-to-vertical anisotropy of 5 and s10 percent in the top 7.5 km of the crust produce synthetic envelopes in general agreement with data. Deeper scattering tends to decrease the initial P wave amplitudes to levels much below those for the data. The synthetics accurately predict Pg, Lg, and PgLg ratios, while Pn and Sn amplitudes and associated ratios are likely biased from erroneous upper mantle SALSA3D Vp and Vs gradients. Array analysis for KSRS data and synthetics using NKNTS events supports our favored statistical models of crustal small-scale heterogeneities. The predominant S wave train for deep double-couple sources very efficiently generates converted SP scattered waves after Pn, in contrast to shallow explosive sources. Both data and simulations show efficient Lg propagation along continental Asia paths and less efficient propagation across the Sea of Japan, consistent with the findings of published simulations for earthquake sources. Topography on the Korean Peninsula can be well approximated by a power-law PSD with an exponent of 3.5.
- Radiofrequency Wave Propagation