Toroidal Mantle Flow Induced by Slab Subduction and Rollback Beneath the Eastern Himalayan Syntaxis and Adjacent Areas


A total of 431 well-defined and 632 null shear-wave splitting measurements obtained from 115 broadband seismic stations located in the eastern Himalayan syntaxis and adjacent areas is largely inconsistent with predicted fast orientations by absolute plate motion models. Spatial coherency analysis of the splitting parameters suggests that the observed azimuthal anisotropy is mostly located in the upper asthenosphere or the transitional layer between the lithosphere and asthenosphere, and the disagreement between the fast orientations and regional tectonic fabrics suggests an insignificant lithospheric contribution to the observed anisotropy. The observations may be attributed to flow systems that are driven by the westward rollback of the Indian slab beneath the Indo-Burma block and are modulated by a previously revealed gap between the northward and eastward subducting slabs of the Indian plate.


Geosciences and Geological and Petroleum Engineering

Research Center/Lab(s)

Center for Research in Energy and Environment (CREE)

Second Research Center/Lab

Center for High Performance Computing Research


This study was partially supported by the China Scholarship Council and Ocean University of China to L. L., by the National Natural Science Foundation of China under award 41876036 to S. L., and by the U.S. National Science Foundation under awards 0911346 and 1830644 to K. L. and S. G.

Keywords and Phrases

Arakan trench; Eastern Himalayan syntaxis; Indian - Eurasian collision; Indo-Burma block; Shear wave splitting

International Standard Serial Number (ISSN)

0094-8276; 1944-8007

Document Type

Article - Journal

Document Version


File Type





© 2019 American Geophysical Union, All rights reserved.

Publication Date

01 Oct 2019