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

Yu-Pin Lin, & Thomas H. Jordan

Published September 11, 2022, SCEC Contribution #12147, 2022 SCEC Annual Meeting Poster #024

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 deforming regions, and does not correlate with crustal temperatures. We explain the data by combining an absorption-band model of low-frequency anelastic attenuation with a Sato-Fehler scattering model featuring crustal velocity heterogeneities having an outer scale of 8 km, a fractal dimension of 3.85, and a root-mean-square amplitude that varies laterally from 5% to 10%. We conclude that elastic scattering from crustal heterogeneities, not anelastic dissipation, dominates high-frequency attenuation. Our results disagree with attenuation models derived from coda-wave analysis.

Citation
Lin, Y., & Jordan, T. H. (2022, 09). High-Frequency Seismic Attenuation in Southern California: Does Elastic Scattering Dominate?. Poster Presentation at 2022 SCEC Annual Meeting.

Related Projects & Working Groups
Seismology