Mantle Reflectivity Structure around Convergent Plate Boundaries
The depth at which mantle constituents go through a phase change provides a very important constraint about the Pressure/Temperature structure of the mantle. Amongst many different metrics, amplitudes of surface reflected shear waves and their precursory arrivals (Figure 1) offer the most complete global coverage due to their insensitivity to the first order source-station distribution.
In collaboration with Yu Jeffrey Gu, Sean Contenti, and Ryan Schultz from the University of Alberta, we use the amplitudes of SS waves and underside reflections from mantle interfaces, which arrive up to ~250-300 s before SS, to investigate subduction related mantle deformations at upper-/mid- mantle depths (see Figure 2).We basically align the seismograms on SS phase, correct for topography (using ETOPO 2) and crustal thickness (using CRUST 5.0), and apply pre-stack depth migration using PREM-predicted travel-time curves. For more information please check Gu et al., (2012) and Contenti et al., (2012). Below are mantle reflectivity cross-sections that traverse northern Japan and Central America.
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