High-Frequency Seismic Attenuation in Southern California: Does Elastic Scattering Dominate?

Yu-Pin Lin, & Thomas H. Jordan

In Preparation August 5, 2022, SCEC Contribution #11963

We measured high-frequency (1-10 Hz) spectral amplitudes of 29,023 P and 22,812 S crustal phases from Southern California earthquakes and separately inverted the two datasets for three-dimensional, frequency-dependent models of total attenuation. The independent estimates of the P and S attenuation factors are nearly equal, decay with wavenumber at approximately the same rate, and are strongly correlated in all three spatial dimensions. Within the seismogenic zone, attenuation is lower in batholithic regions, higher in heavily faulted regions, and does not correlate with crustal temperatures. The data can be explained by an isotropic Sato-Fehler scattering model that has heterogeneities in the upper and mid crust with an outer scale of 6 km, a fractal dimension of 3.8, and root-mean-square amplitudes that vary laterally from 5% to 10%. Our results are inconsistent with the attenuation behavior inferred from envelopes of S waves and their coda, but the reasons for this discrepancy are unclear.

Citation
Lin, Y., & Jordan, T. H. (2022). High-Frequency Seismic Attenuation in Southern California: Does Elastic Scattering Dominate?. Geophysical Research Letters, (in preparation).