Isotropic High‐Frequency Radiation in Near‐Fault Seismic Data
Year: 2024
Type: article
Abstract: We compare Fourier Amplitude Spectra of Fault Normal (FN) and Fault Parallel (FP) seismograms at near‐fault sites for seven strike‐slip earthquakes with moment magnitudes M w ≥ 6. For all events we find large FN/FP ratios at low frequencies consistent with near‐fault S ‐wave radiation patterns for strike‐slip earthquakes. However, the difference diminishes with increasing frequency and FN/FP is about 1 above a transition frequency. The results may reflect small tensile/isotropic components in the earthquake rupture zones that homogenize the high‐frequency radiation in different directions at near‐fault sites. The FN/FP ratios at low frequencies and transition frequencies above which FN ∼ FP vary among the analyzed earthquakes and have no clear correlation with the magnitudes. The lack of correlation may signify a characteristic scale (e.g., process zone size, duration of source time function) controlling the isotropic radiation, and/or wave propagation and other effects that mask the source effects.
Source: Geophysical Research Letters
DOI: 10.1029/2024gl110303
Authors: Yehuda Ben‐Zion, Siyuan Zhang, Xiaofeng Meng
Language: English
Subfield: Geophysics
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,900
OpenAlex ID: W4402088030