Journal ArticlePrediction of Complex Observed Shear Wave Splitting Patterns at Ryukyu Subduction Zone Using a Strong Intra‐Slab Anisotropy ModelAppini, Sharmila [Department of Earth and Atmospheric Sciences University of Houston Houston TX USA] (ORCID:0009000478227499); Li, Jiaxuan [Department of Earth and Atmospheric Sciences University of Houston Houston TX USA] (ORCID:0000000237660876); Hu, Hao [School of Geosciences The University of Oklahoma Norman OK USA] (ORCID:0000000337912954); Creasy, Neala [Los Alamos National Laboratory Los Alamos NM USA] (ORCID:0000000225576247); Thomsen, Leon [Department of Earth and Atmospheric Sciences University of Houston Houston TX USA]; McNease, Joseph [Department of Earth and Atmospheric Sciences University of Houston Houston TX USA]; Zheng, Yingcai [Department of Earth and Atmospheric Sciences University of Houston Houston TX USA] (ORCID:0000000191798940)<title>Abstract</title> <p>Complex shear wave splitting (SWS) patterns in subduction zones are often interpreted geodynamically as resulting from complex mantle flow; however, this may not always be necessary. We analyzed 7,093 high‐quality SWS measurements from teleseismic S waves recorded by Hi‐net stations across the Ryukyu arc in Japan. Our findings show a systematic rotation of the fast S polarization from trench‐parallel to trench‐perpendicular depending on the earthquake backazimuth. For the same earthquake, the measured splitting patterns also vary spatially across the southwest Japan. Using full‐wave seismic modeling, we showed that a dipping slab with ∼30% shear anisotropy of the tilted transverse isotropy (TTI) type, with a symmetry axis perpendicular to the slab interface, can predict the observed delay times and polarization rotation. Our results highlight the importance of considering dipping anisotropic slabs in interpreting SWS at subduction zones.</p>American Geophysical Union2025-02-1610647268Geophysical Research Letters5230094-8276https://doi.org/10.1029/2024GL1111312027150National Science Foundation