Upper mantle anisotropy in the New Zealand Region
- 15 May 1999
- journal article
- Published by American Geophysical Union (AGU) in Geophysical Research Letters
- Vol. 26 (10) , 1497-1500
- https://doi.org/10.1029/1999gl900273
Abstract
Shear‐wave splitting parameters of fast polarization direction (Φ) and delay time (δt) are determined using data from the Southern Alps Passive Seismic Experiment (SAPSE), on the South Island of New Zealand and in the surrounding region. Our results clearly show that Φ are subparallel to trends of the Alpine and Marlborough Faults, and to the Pacific‐Australian plate boundary. The δt values range from 0.6–2.2 s with an average value of 1.6 s; the largest values are from the central South Island. The main source of the observed shear‐wave splitting is an anisotropic region between 40–400 km. The width of the zone is approximately 200 km. We attribute the coincidence of surface structural trends with the measured Φ, and the large δt values, to significant shear deformation in a 200 km thick zone along the plate boundary extending from the surface to deep within the upper mantle.Keywords
This publication has 20 references indexed in Scilit:
- SKS splitting and the seismic anisotropy of the mantle beneath the Hikurangi subduction zone, New ZealandPhysics of the Earth and Planetary Interiors, 1996
- Seismic anisotropy in the fore-arc region of the Hikurangi subduction zone, New ZealandPhysics of the Earth and Planetary Interiors, 1996
- Laboratory and seismological observations of lower mantle isotropyGeophysical Research Letters, 1995
- Effect of recent revisions to the geomagnetic reversal time scale on estimates of current plate motionsGeophysical Research Letters, 1994
- Anatomy, structural evolution, and slip rate of a plate-boundary thrust: The Alpine fault at Gaunt Creek, Westland, New ZealandGSA Bulletin, 1994
- Interpretation of SKS-waves using samples from the subcontinental lithospherePhysics of the Earth and Planetary Interiors, 1993
- Current plate velocities relative to the hotspots incorporating the NUVEL‐1 global plate motion modelGeophysical Research Letters, 1990
- Cretaceous geotectonic patterns in the New Zealand RegionTectonics, 1989
- Age and origin of the New Zealand Orocline in relation to Alpine Fault movementJournal of the Geological Society, 1987
- Seismic Anisotropy of the Uppermost Mantle under OceansNature, 1964