AUTHOR=Fuji Nobuaki , Jang Hyoihn , Nakao Atsushi , Kim YoungHee , Fernández-Blanco David , Lee Sang-Mook , Schroeder Alexia , Konishi Kensuke TITLE=A Possible Roll-Over Slab Geometry Under the Caroline Plate Imaged by Monte Carlo Finite-Frequency Traveltime Inversion of Teleseismic SS Phases JOURNAL=Frontiers in Earth Science VOLUME=9 YEAR=2021 URL=https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2021.593947 DOI=10.3389/feart.2021.593947 ISSN=2296-6463 ABSTRACT=

The shape of a subducting slab varies as a function of trench motion. Two end-members of subduction modes are geodynamically possible: roll-back mode underneath neighboring plates and roll-over mode underneath the plate itself. Whereas most of major slabs seem to roll back while the Pacific plate shows a slab piling behavior down to ∼1,000 km depth under the Mariana trench, no clear evidence of slab roll-over in nature has been reported so far. Here we show a possible roll-over slab beneath the Caroline microplate, revealed from its three-dimensional seismic velocity structure derived by analyzing teleseismic reverberating SS phases. We suggest that slab roll-over is driven by at least two factors: 1) the overall buoyancy and fragility of the Caroline microplate at the surface, induced by a thin hot mantle plume that rises from depths ≥800 km; and 2) the pushing force of the Pacific plate acting on the trailing edge of the Caroline plate.