Mid mantle scatterers near the Mariana Slab detected with a double array method

Abstract

We use a cluster of deep earthquakes, the fore‐ and aftershocks of the 23‐AUG‐1995 Mw=7.1 (18.8N, 145.3E, h=595 km) event in the Mariana subduction zone as source array to locate where waves scatter near the deep slab. In order to obtain the high‐precision location needed in this context, we first relocate the events with a modified master event technique. Using the double beam method on the relocated events and data from the Warramunga array in Australia, we identified two non‐standard S‐to‐P conversions arriving about 20.5 and 24 s after the P‐wave. The corresponding scatterers are approximately located at a depth of 790 km (720 km) and a distance of 0.9° to the southeast (2.3° to the southwest) of the main shock. The scatterers positions correspond to the location of lithosphere subducted below the 660 km discontinuity.