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Abstract TheH‐κmethod (Zhu & Kanamori, 2000,https://doi.org/10.1029/1999JB900322) has been widely used to estimate the crustal thickness (H) and the ratio ofPtoSvelocities (VP/VSratio,κ) with receiver functions. However, in regions where the crustal structure is complicated, the method may produce biased results, arising particularly from dipping Moho and/or crustal anisotropy.H‐κstacking in case of azimuthal or radial anisotropy with flat Moho has been proposed but not for cases with plunging anisotropy and dipping Moho. Here we propose a generalizedH‐κmethod calledH‐κ‐c, which corrects for these effects first before stacking. We consider rather general cases, including plunging anisotropy and dipping interfaces of multiple layers, and use harmonic functions to correct for arrival time variations ofPsand its crustal multiples with back azimuth (θ). Systematic synthetic tests show that the arrival time variations can be well fitted by cosθand cos2θfunctions even for very complex crustal structures. Correcting for the back azimuthal variations significantly enhancesH‐κstacking. We verify the feasibility of theH‐κ‐c method by applying it to 40 permanent stations in various geological setting across the Mainland China. The results show clear improvement after the harmonic corrections, with clearer multiples and stronger stacking energy, as well as more reliableH‐κvalues. Large differences inH(up to 5.0 km) andκ(up to 0.09) between the new and traditional methods occur mostly in mountainous regions, where the crustal structure tends to be more complex. We caution in particular about systematic bias when the traditional method is used in the presence of dipping interfaces. The modified method is simple and applicable anywhere in the world.
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Radial Anisotropy in Receiver Function H-κ Stacks
Abstract Receiver functions can be used to estimate the Moho depth (H) and ratio of P to S wavespeed (α/β or κ) in the crust. This is commonly done by grid search, forward modeling travel times to produce so-called “H-κ” stacks of receiver function amplitude. However, radial anisotropy in the crust, which can be significant, is almost never considered in this process. Here, we show that radial anisotropy changes the H-κ stack, biasing interpretations of crustal structure by introducing errors up to ∼3% in H and ∼1% in κ for commonly observed anisotropy magnitudes. We propose a simple method to correct H-κ stacks by incorporating radial anisotropy in the forward calculation. Synthetic tests show that this approach almost completely removes error caused by radial anisotropy. We show examples of this procedure with stations in the eastern United States. We provide readers with code to construct radially anisotropic H-κ stacks.
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- Award ID(s):
- 1753722
- PAR ID:
- 10467746
- Publisher / Repository:
- Seismological Research Letters
- Date Published:
- Journal Name:
- Seismological Research Letters
- ISSN:
- 0895-0695
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1785/0220230114
