Seismic velocity and anisotropy tomography of southern Sumatra

TitleSeismic velocity and anisotropy tomography of southern Sumatra
Publication TypeJournal Article
Year of Publication2021
AuthorsLiu Y, Suardi I, Huang X, Liu S, Tong P
JournalPhysics of the Earth and Planetary Interiors
Date Published07/2021
Other NumbersArticle number: 106722

In this study new isotropic P- and S-wave velocity models as well as the P-wave azimuthally anisotropic model of the crust and uppermost mantle beneath southern Sumatra are derived from regional earthquake data by using the eikonal equation-based seismic tomography method. All the tomographic results reveal a clear high-velocity (high-V) belt in the uppermost mantle that represents the subducting Indo-Australian slab. In the mantle wedge, relatively low velocity (low-V) anomalies are clearly imaged, which may be related to the ascending fluids and partial melts caused by slab dehydration. The P-wave azimuthally anisotropic model shows complex patterns in the upper crust, which may be due to the effects of the maximum horizontal compressive stress and/or geological structure. Trench-normal fast velocity directions (FVDs) prevail in the lower crust, which may be associated with the plastic flow induced by the oblique plate convergence. Predominant trench-parallel FVDs in the fore-arc and volcanic-arc mantle wedge and trench-normal FVDs in the back-arc mantle wedge are observable, which are possibly related to 2-D slab-driven corner flow and/or 3-D complex mantle flow. The subducting slab generally displays trench-parallel FVDs, suggesting that the slab may keep the original fossil anisotropy.