Slab Morphology Around the Philippine Sea: New Insights From P‐Wave Mantle Tomography
Lijuan She, Guibin Zhang, Guoming Jiang, Dapeng Zhao, Jiaji Xi, Qingtian Lü, Danian Shi
Abstract
Abstract We apply seismic tomography to 590,213 P‐wave arrival‐time data of 23,486 local earthquakes and 300,051 relative travel‐time residuals of 27,492 teleseismic events to study the 3‐D velocity structure of the crust and upper mantle beneath the entire Philippine Sea Plate (PSP) and its adjacent areas. Our results reveal significant high‐velocity anomalies beneath the Philippine Trench, the Japan‐Izu‐Bonin‐Mariana Trench, and the Nankai Trough, which reflect the subducted Philippine Sea slab, the Pacific slab, and the Shikoku Basin, respectively. On the basis of the tomographic images, we construct morphological models of these slabs. The slab morphologies become complex from the east to west. Taking into account previous results of geochemistry, paleomagnetism and numerical simulations, we deem that the complicated morphologies of the subducted slabs are related to the slab age, subduction rate, collision between different plates, clockwise rotation of the PSP, and retreat rate of trenches.