Fig. 14

Results of forward modeling of receiver functions for various models of LVL-750. a The velocity-depth relationship for various models of a LVL at ~ 750 km. b Corresponding receiver function. Three models are considered: (1) A low velocity channel cause by the presence of chemically distinct materials such as subducted oceanic crust (e.g., (Gréaux et al. 2019)). (2) A case for a heavy melt. In a region of down-welling background flow (i.e., subduction zones), heavy melt will drain down and there is no melt accumulation. Consequently, velocity is only slightly lower than the background velocity. (3) A case for a light melt. Light melt will be accumulated in s region of down-welling background flow (i.e., subduction zones) and a melt-rich layer will be formed resulting in a substantial velocity reduction near the top of the melt-rich layer