Mapping the Moho beneath the Southern Alps continent‐continent collision, New Zealand, using wide‐angle reflections

Abstract

A wide‐angle stack using all onshore‐offshore, and onshore seismic data from the SIGHT'96 experiment provides a direct three‐dimensional (3‐D) image of the Moho below the continental collision zone through the South Island of New Zealand. A bright reflector sequence (up to 4 s thick), the base of which coincides with the PmP modeled Moho, extends throughout most of the lower crust and bends downward asymmetrically beneath the Southern Alps. The crustal root reaches a maximum depth at ∼15 s (45 km), beneath the regional (−80 mGal) Bouguer gravity low and is flanked east and west by shallower Moho where the average crustal thickness is ∼20 km. The 3‐D structure of the crustal root in the central South island is moderately well resolved by the SIGHT'96 experiment.