Regional Wave Propagation Including Small-Scale Heterogeneities and Q(f)
Abstract
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 s=10 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 Pg/Lg 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.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 30, 2019
- Accession Number
- AD1082225
Entities
People
- Kim Olsen
- Te-yang Yeh
Organizations
- San Diego State University