An Effective Method to Extract Overtones of Surface Wave From Array Seismic Records of Earthquake Events

Abstract

Surface wave dispersion curves are extensively used to map the lithospheric shear‐wave velocity structures. However, traditional methods have difficulty extracting overtone dispersion curves from both ambient noise and seismic event data. Recently, Wang et al. (2019, https://doi.org/10.1029/2018JB016595) proposed a new array‐based method, the frequency‐Bessel transform (F‐J) method, to extract high frequency overtones from ambient noise data. However, because the Green's functions of earthquakes are complex, the F‐J method cannot be directly applied to extract overtones from earthquake event data. In this paper, we analyze the differences between ambient noise and earthquake event data and verify that the F‐J method can be efficiently applied to event data by controlling the azimuthal range and adopting time windows. For the F‐J method using earthquake records, the time windows calculated by group velocity intervals can improve the overtone extraction efficiency. We named this application of the F‐J method with time windows using event data the multiwindow F‐J (MWFJ) method to distinguish the two techniques. Further verifications were performed using real data from three earthquakes recorded by the U.S. Transportable Array. Compared to traditional methods for extracting overtones from earthquakes, the MWFJ method can effectively extract higher‐frequency (0.02–0.4 Hz, for the data used in this work) and higher‐resolution overtones from event data. Moreover, the overtones extracted from earthquakes are more sensitive to deeper structures than those extracted from ambient noise. The complementarity of the F‐J and MWFJ methods for the extraction of overtones indicates that better imaging results may be obtained by combining these two methods.

Multiple Leaking Mode Dispersion Observations and Applications From Ambient Noise Cross‐Correlation in Oklahoma

“…(2019) introduced this method to extract the overtone dispersion of ambient noise. Li & Chen (2020) confirmed the feasibility of this method on earthquake records. The F‐J method was applied in this work to extract the leaking mode dispersion from ambient noise cross‐correlation.…”

Constraints on Crustal P Wave Structure With Leaking Mode Dispersion Curves

“…(2019) proved that if only contains the integral item, is equivalent to the TDS , which means that the F‐J method can be used in the overtone surface wave dispersion extraction of ambient noise and is not limited to the arrangement of stations. Subsequently, Li and Chen (2020) verified the applicability of this method for earthquake records. Hu et al.…”

The Frequency‐Bessel Spectrograms of Multicomponent Cross‐Correlation Functions From Seismic Ambient Noise

“…However, although the F‐J method has been successfully applied to active and passive source data to extract multimode surface wave dispersion curves (Li & Chen, 2020; Wang et al., 2019; Wu et al., 2019; Yang et al., 2019), it currently can only deal with ZZ component CCFs. On the one hand, other‐component CCFs provide complementary information of the Earth's structure (Aki, 1957; Gribler & Mikesell, 2019; Haney et al., 2012; Xia, 2014).…”