Low velocity channels in the oceanic asthenosphere from full waveform inversion using the Spectral Element Method
From Berkeley Global Seismology Group
Science, 11 October 2013, Vol. 342, pp. 227-230
Scott French, Vedran Lekic, Barbara Romanowicz
Abstract:
Understanding the relationship between different scales of convection that drive plate motions and hotspot volcanism still eludes geophysicists. Using full-waveform seismic tomography, we imaged a pattern of horizontally elongated bands of low shear velocity, most prominent between 200 and 350 kilometers depth, which extends below the well-developed low-velocity zone.These quasi-periodic fingerlike structures of wavelength ~2000 kilometers align parallel to the direction of absolute plate motion for thousands of kilometers. Below 400 kilometers depth, velocity structure is organized into fewer, undulating but vertically coherent, low-velocity plumelike features, which appear rooted in the lower mantle. This suggests the presence of a dynamic interplay between plate-driven flow in the low-velocity zone and active influx of low-rigidity material from deep mantle sources deflected horizontally beneath the moving top boundary layer.
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See related papers:
Lekic, V. and B. Romanowicz (2011) Inferring mantle structure by full waveform tomography using the Spectral Element Method, Geophys. J. Int., 185, 799-831, doi:10.1111/j.1365-246X.2011.04969.x.
Lekic, V. and B. Romanowicz (2011) Tectonic regionalization without a priori information: a cluster analysis of upper mantle tomography, Earth Planet. Sci. Lett., 308, 151-160. doi:10.1016/j.epsl.2011.05.050.
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