Seismic Evidence for Sharp Lithosphere-Asthenosphere Boundaries of Oceanic Plates

摘要: The mobility of the lithosphere over a weaker asthenosphere constitutes essential element plate tectonics, and thus understanding processes at lithosphere-asthenosphere boundary (LAB) is fundamental to understand how our planet works. It especially so for oceanic plates because their relatively simple creation evolution should enable easy elucidation LAB. Data from borehole broadband ocean bottom seismometers show that LAB beneath Pacific Philippine Sea sharp age-dependent. observed large shear wave velocity reduction requires partially molten consisting horizontal melt-rich layers embedded in meltless mantle, which accounts viscosity contrast facilitates motions.