A mantle thermometer
Article Abstract:
Measurements of deep earthquakes by seismometers can be used to create images of faint near-surface reflections from seismic discontinuities in the upper mantle near subducting slabs. This can indicate how the influx of cold oceanic lithosphere is affecting rocks hundreds of kilometers beneath the surface. John E. Vidale and Harley M. Benz developed this technique for finding out the make-up of subduction zones far from where the seismometers are located. The technique discovered reflections from a discontinuity occurring at 210 kilometers that may be the base of the asthenosphere.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1992
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Excitation of true polar wander by subduction
Article Abstract:
Activity in subduction zones can cause true polar wander (TPW) only if the Earth's upper mantle is 10 times less viscous than the lower mantle. TPW, which occurs when the mantle moves with respect to the Earth's rotation axis, has happened in episodes of comparatively high velocity since the Late Cretaceous period. Analysis using nonlinear Liouville equations shows that rheological changes within the mantle both triggered TPW and kept it from continuing indefinitely.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1992
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Deformation of a weak subducted slab and variation of seismicity with depth
Article Abstract:
The oceanic lithosphere has platelike properties even when descending into the Earth's mantle. However, lithospheric slabs have been shown to deform noticeably when subjected to subduction, becoming more liquid than solid. Deep earthquakes had previously been related to solid slabs' deformation, but an analysis of stress on high-viscosity fluid slabs reveals a correlation with seismicity rates.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1993
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