Mantle Seismic Structure Beneath the MELT Region of the East Pacific Rise from P and S Wave Tomography

Relative travel time delays of teleseismic P and S waves, recorded during the Mantle Electromagnetic and Tomography (MELT) Experiment, have been inverted tomographically for upper-mantle structure beneath the southern East Pacific Rise. A broad zone of low seismic velocities extends beneath the rise...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 1998-05, Vol.280 (5367), p.1224-1227
Main Authors: Toomey, Douglas R., William S. D. Wilcock, Solomon, Sean C., Hammond, William C., Orcutt, John A.
Format: Article
Language:English
Subjects:
Angle of incidence
Anisotropy
Congenital Impairments
Crystalline rocks
Earth
Earth sciences
Earth, ocean, space
Exact sciences and technology
Geology
Geophysical research
Igneous and metamorphic rocks petrology, volcanic processes, magmas
Internal geophysics
Mantle
Mantle (Geology)
Marine
Networks
Ocean floor
Oceans
P waves
Propagation delay
S waves
Seismology
Solid-earth geophysics, tectonophysics, gravimetry
Statistical variance
The MELT Experiment
Travel time
Upwelling water
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Summary:Relative travel time delays of teleseismic P and S waves, recorded during the Mantle Electromagnetic and Tomography (MELT) Experiment, have been inverted tomographically for upper-mantle structure beneath the southern East Pacific Rise. A broad zone of low seismic velocities extends beneath the rise to depths of about 200 kilometers and is centered to the west of the spreading center. The magnitudes of the P and S wave anomalies require the presence of retained mantle melt; the melt fraction near the rise exceeds the fraction 300 kilometers off axis by as little as 1%. Seismic anisotropy, induced by mantle flow, is evident in the P wave delays at near-vertical incidence and is consistent with a half-width of mantle upwelling of about 100 km.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.280.5367.1224