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Published November 12, 1999 | public
Journal Article

Evidence for a Ubiquitous Seismic Discontinuity at the Base of the Mantle

Abstract

A sharp discontinuity at the base of Earth's mantle has been suggested from seismic waveform studies; the observed travel time and amplitude variations have been interpreted as changes in the depth of a spatially intermittent discontinuity. Most of the observed variations in travel times and the spatial intermittance of the seismic triplication can be reproduced by a ubiquitous first-order discontinuity superimposed on global seismic velocity structure derived from tomography. The observations can be modeled by a solid-solid phase transition that has a 200-kilometer elevation above the core-mantle boundary under adiabatic temperatures and a Clapeyron slope of about 6 megapascal per kelvin.

Additional Information

© 1999 American Association for the Advancement of Science. Received for publication 19 July 1999; accepted for publication 14 October 1999. We thank S. Grand for access to his tomography model and T. Lay and E. Garnero for providing the D0 triplication travel time data. Two anonymous reviewers provided a number of valuable comments and suggestions. Supported by NSF grant EAR-9809771. This is contribution no. 8664, Division of Geological and Planetary Sciences, California Institute of Technology.

Additional details

Created:
August 19, 2023
Modified:
October 20, 2023