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Illuminating the plate interface structure beneath Cook Strait, New Zealand, with receiver functions
Department of Geological Sciences, University of Colorado at Boulder, Boulder, Colorado, USA
Institute of Geophysics, School of Earth Sciences, Victoria University of Wellington, Wellington, New Zealand
Department of Geological Sciences, University of Colorado at Boulder, Boulder, Colorado, USA
Department of Geological Sciences, University of Colorado at Boulder, Boulder, Colorado, USA
Using teleseismic receiver functions derived from broadband seismic arrays on the north end of the South Island and south end of the North Island of New Zealand, we image seismic impedance discontinuities in the upper mantle beneath Cook Strait using common conversion point (CCP) and Kirchhoff migration methods. Our primary findings are observations of discontinuities associated with the top of the subducting Pacific Plate. Our results suggest that contrary to recent suggestions, the plate is continuous under the northern South Island through the region of seismicity deeper than 50 km. West of Cook Strait, the slab dips steeply to the northwest. We find evidence for a low-velocity layer at the top of the slab, near which much of the seismicity is concentrated. We see hints of two crustal discontinuities, consistent with observations from previous studies. We also see substantial and continuous energy on the transverse receiver function stacks above the mantle wedge extending to the northwestern edge of our stacks, which may indicate seismic anisotropy above 50 km depth.
Received 8 June 2006; accepted 26 March 2007; published 27 June 2007.
Citation: (2007), Illuminating the plate interface structure beneath Cook Strait, New Zealand, with receiver functions, J. Geophys. Res., 112, B06310, doi:10.1029/2006JB004552.
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