Continuous deformation versus faulting through the continental lithosphere of new zealand.

Molnar, P; Anderson, HJ; Audoine, E; Eberhart-Phillips, D; Gledhill, KR; Klosko, ER; McEvilly, TV; Okaya, D et al. · Science · 1999

basic_science · Level V

Where this comes from

Abstract

Seismic anisotropy and P-wave delays in New Zealand imply widespread deformation in the underlying mantle, not slip on a narrow fault zone, which is characteristic of plate boundaries in oceanic regions. Large magnitudes of shear-wave splitting and orientations of fast polarization parallel to the Alpine fault show that pervasive simple shear of the mantle lithosphere has accommodated the cumulative strike-slip plate motion. Variations in P-wave residuals across the Southern Alps rule out underthrusting of one slab of mantle lithosphere beneath another but permit continuous deformation of lithosphere shortened by about 100 kilometers since 6 to 7 million years ago.