[SIT28-P08] Construction of stable S receiver function and its application to observations of seismic discontinuities in the lithosphere-asthenosphere system beneath South Korea
Keywords:S receiver function, lithosphere-asthenosphere system
To devise an objective criterion to minimize the interference from P coda waves, as a proof of concept, we first examine SRFs recorded in South Korea seismic network, sitting on a geologically stable continental platform. Through systematic analysis of full-waveform synthetic waveforms and SRFs from realistic focal mechanisms and source depths, we find the systematics that, when the mean amplitude of P coda waves is comparably stronger than the S wave recorded in the radial component, SRFs from 1-D IASP91 model display strong and dubious arrivals. Furthermore, if the mean amplitude of SRFs after the S wave is large, dubious signals of SRFs before the S arrival become strong as well. It is conceivable that these signals may be mistakenly interpreted as S-to-P converted waves beneath seismic stations.
We devise measures of ZRR, the amplitude ratio between vertical P coda waves and radial S waves, and AMP, the amplitude of SRFs after the S arrival and systematically test how ZRR and AMP threshold may be used to detect and retain robust S-to-P converted waves. We will demonstrate the effectiveness of our new data selection criteria, which not only provides a more robust and consistent observation of S-to-P converted waves in a broad frequency band between 0.1 Hz and 1 Hz, but offers a great potential to better characterize seismic discontinuities in the LAS.