Low velocity channels in the oceanic asthenosphere from full waveform inversion using the Spectral Element Method

From Berkeley Global Seismology Group
Jump to: navigation, search

Science, 11 October 2013, Vol. 342, pp. 227-230

Scott French, Vedran Lekic, Barbara Romanowicz


Understanding the relationship between different scales of convection that drive plate motions and hotspot volcanism still eludes
Example alt text
3D view of seismic shear-wave velocity anomalies in the upper 1000 km of the earth's mantle beneath the central Pacific, showing the relationship between the seismically-slow "plumes" and channels imaged in the study. Green cones at the surface correspond to the locations of ocean islands associated with "hot-spot" volcanism (e.g. Hawaii).
Example alt text
A map view of seismic shear-wave speed in the earth's upper mantle, highlighting the slow wave-speed channels (warm colors) imaged in this study. Where present, the channels align with the direction of tectonic-plate motion (dashed lines).
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.

Click here to learn more about the SEMum2 Model, a global radially anisotropic shear-velocity model of the earth's upper mantle and transition zone.

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.


UC Berkeley NewsCenter

NERSC Science Highlight

The Los Angeles Times

Return to research highlights

Personal tools
BGSG Internal