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Slab Morphology and Mantle Wedge Processes in the Tonga Subduction Zone Revealed by Body-wave Double-difference Tomography

Description: 

The Tonga subduction zone has the fastest convergence rate, and hosts about two-thirds of the world’s deep-focus earthquakes (300-700 km). Previous studies of deep-focus earthquakes suggest a relic slab separated from the Tonga slab beneath the Fiji islands. Moreover, the mantle wedge dynamics are complicated beneath the Lau Back-arc Basin, as the slab-controlled flux melting interacts with the decompression melting beneath back-arc centers. In this study, we use both regional and global body wave datasets to image the Tonga subduction zone to about 800 km depth. The regional datasets include arrivals from ocean bottom and land-based temporary seismograph deployments. In our results, the high-velocity slab extends beyond the bottom of the mantle transition zone (MTZ), at least 200 km away from a separate high-velocity structure in the MTZ to its west. This high-resolution 3D velocity model will provide valuable information on the subduction dynamics, mantle wedge melting processes, and the origin of abundant deep earthquakes in the Tonga subduction zone.

Session: Earth’s Structure from the Crust to the Core [Poster Session]

Type: Poster

Date: 5/2/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Fan

Student Presenter: Yes

Invited Presentation: 

Authors