Shear‐Dominant Continental Rifting in Northern Ryukyu Revealed by Ambient Noise Tomography

Researchers have uncovered evidence of shear-dominant continental rifting in the northern Ryukyu Arc, challenging traditional models of backarc extension. Using ambient noise tomography with ocean-bottom seismometer data, they revealed distinct crustal deformation structures, including arc-parallel and arc-perpendicular seismic anisotropy in the upper to mid-crust and lower crust to uppermost mantle, respectively. The findings suggest that vertical shearing from right-lateral arc retreat and horizontal shearing from mantle wedge corner flow drive the rifting process. Additionally, arc-perpendicular anisotropy in the forearc upper crust may indicate crack alignment due to the Amami Plateau collision. This study highlights the transtensional nature of the northern Ryukyu rift system, offering new insights into continental rifting mechanisms.

Chen, K.-X., Kuo, B.-Y., Lin, T.-J., Lin, P.-Y. P., Gung, Y., Tan, E., Kodaira, S., Ishihara, Y., Nakamura, M., Arai, R., Lee, F.-Y., Hung, S.-H., Chen, K. H., Lin, C.-R., & Wang, C.-C. (2024). Shear‐Dominant Continental Rifting in Northern Ryukyu Revealed by Ambient Noise Tomography. Journal of Geophysical Research: Solid Earth, 129(11). Portico. https://doi.org/10.1029/2024jb029448