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A Deep Dry Slab Core Beneath the Japan Sea Revealed by Inter-source Interferometry

The intermediate- (10-100 km) and small-scale (<10 km) slab structures below 410 km are important manifestations of various thermal and petrological processes. However, seismic imaging of these structures has been particularly challenging because the seismograms recorded on the surface can be easily complicated by shallow structures. To resolve the subtle seismic signatures from deep slabs without influence from shallow complexities, we apply a novel inter-source interferometry method that turns deep earthquakes into virtual seismometers closer to the target. Using data from Hi-net, we not only present strong evidence for an intermediate-scale metastable olivine wedge and small-scale intra-slab heterogeneity beneath the Japan Sea, but also constrain their dimensions and velocity perturbations more accurately than before. The results suggest that the initiation mechanism of deep earthquakes is due to transformational faulting of metastable olivine, while revealing petrologic processes associated with dehydration of subducting slabs. Beyond the relatively independent scales of slab structures and dynamics, our findings point toward a consistent picture of a dry slab core below 410 km beneath the Japan Sea.

Session: Structure and Seismogenesis of Subducting Slabs [Poster]

Type: Poster

Room: Evergreen Ballroom

Date: 4/22/2022

Presentation Time: 08:00 AM Pacific

Presenting Author: Zhichao Shen

Student Presenter: Yes

Additional Authors