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Constraints on the lateral strength of slabs from three-dimensional dynamic flow models

Moresi, Louis and Gurnis, Michael (1996) Constraints on the lateral strength of slabs from three-dimensional dynamic flow models. Earth and Planetary Science Letters, 138 (1-4). pp. 15-28. ISSN 0012-821X. doi:10.1016/0012-821X(95)00221-W.

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If the viscosity of subducted lithosphere is described purely by temperature and pressure, it should remain considerably more viscous than the surrounding material as it descends through the upper mantle. Many dynamic models of the long wavelength geoid associated with slabs require an increase in viscosity from the upper to the lower mantle but assume the perturbation to the lateral viscosity structure arising from the slabs themselves can be ignored. Previous studies indicate that strong and localized viscosity variations should have a dramatic influence on the geoid. We present 3D finite element models of the regional geoid of the Western Pacific subduction zones. Slab buoyancies and viscosities are defined using the distribution of seismicity. The geoid is very sensitive to the lateral strength of the slab. Very viscous slabs penetrating a low viscosity mantle generate significant (10–50 m) long wavelength geoid lows: opposite to the geoid high which is observed over slabs. To obtain a geoid high comparable to that observed, the lower mantle viscosity must be 60–200 times greater than the upper mantle viscosity and the slab must be in contact with the lower mantle. These strict requirements suggest that slabs have been weakened and cannot act as stress guides from the deep mantle to the surface.

Item Type:Article
Related URLs:
URLURL TypeDescription
Moresi, Louis0000-0003-3685-174X
Gurnis, Michael0000-0003-1704-597X
Additional Information:© 1996 Elsevier Science B.V. Received 20 July 1995; accepted 14 November 1995. The authors would like to thank D. Yuen and two anonymous referees for their helpful comments. This research was supported by the David and Lucille Packard Foundation and NSF grant EAR-9496185. Contribution 5565 of the Division of Geological and Planetary Sciences, California Institute of Technology.
Group:Seismological Laboratory
Funding AgencyGrant Number
David and Lucille Packard FoundationUNSPECIFIED
Subject Keywords:Western Pacific; 10°N to 50°N; subduction zones; lithosphere; viscosity
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Other Numbering System NameOther Numbering System ID
Caltech Division of Geological and Planetary Sciences5565
Issue or Number:1-4
Record Number:CaltechAUTHORS:20130212-080951914
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Official Citation:Louis Moresi, Michael Gurnis, Constraints on the lateral strength of slabs from three-dimensional dynamic flow models, Earth and Planetary Science Letters, Volume 138, Issues 1–4, February 1996, Pages 15-28, ISSN 0012-821X, 10.1016/0012-821X(95)00221-W.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:36862
Deposited By: Tony Diaz
Deposited On:25 Feb 2013 21:53
Last Modified:09 Nov 2021 23:25

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