Publication Date:
1999-04-02
Description:
Observations of core-diffracted P (Pdiff) and SH (SHdiff) waves recorded by the Missouri-to-Massachusetts (MOMA) seismic array show that the ratio of compressional (P) seismic velocities to horizontal shear (SH) velocities at the base of the mantle changes abruptly from beneath the mid-Pacific (VP/VS = 1.88, also the value predicted by reference Earth models) to beneath Alaska (VP/VS = 1.83). This change signifies a sudden lateral variation in material properties that may have a mineralogical or textural origin. A textural change could be a result of shear stresses induced during the arrival at the core of ancient lithosphere from the northern Pacific paleotrench.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wysession -- Langenhorst -- Fouch -- Fischer -- Al-Eqabi -- Shore -- Clarke -- New York, N.Y. -- Science. 1999 Apr 2;284(5411):120-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Earth and Planetary Sciences, Washington University, St. Louis, MO 63130, USA. Department of Geological Sciences, Northwestern University, Evanston, IL 60208, USA. Department of Geological Sciences, Brown University, Provide.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/10102807" target="_blank"〉PubMed〈/a〉
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
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Chemistry and Pharmacology
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Computer Science
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Medicine
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Natural Sciences in General
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Physics
