Accession Number : ADP204478

Title :   Elastic and Anelastic Structure Beneath Eurasia,

Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF EARTH ATMOSPHERIC AND PLANETARY SCIENCES

Personal Author(s) : Ekstroem, Goeran ; Dziewonski, Adam M. ; Su, Wei-jia ; Smith, Gideon P.

PDF Url : ADP204478

Report Date : 14 AUG 1995

Pagination or Media Count : 9

Abstract : We are collecting and analyzing large and diverse datasets of seismic waveforms, absolute and relative body wave traveltimes, and surface wave phase velocities and amplitudes. Our primary objective is to map the variations of elastic mantle properties beneath Eurasia over horizontal lengthscales of approximately 1000-1500 km and vertical lengthscales of 50-100 km. In comparison with recent Harvard global models, such as S12WM13, we have increased the horizontal resolution by expanding the global structure up to spherical harmonic degree l = 20, and we have adopted a radial parameterization which gives better vertical resolution in the upper mantle. Using earlier and new datasets, we have derived a new whole mantle model, S20U7L5. The new model shows many of the same features seen in previous tomographic images, but with significantly sharper definition, in particular in the upper mantle. Lithospheric roots beneath the stable continental interiors are the most prominent feature in the uppermost mantle. The model is partially validated by comparisons with the earlier regional models SNA and TNA. While there is striking similarity in the velocity structure beneath a great variety of continental interiors, West Africa appears to overlie one of the fastest locations in the upper mantle, with faster than average velocities extending to 500 km depth. Additional tasks to be completed before the new model is finalized is the incorporation of more accurate corrections for crustal thickness and structure, as well as the inclusion of an extensive dataset of recently measured teleseismic traveltimes.

Descriptors :   *SEISMIC DETECTION, *EARTH CRUST, *SEISMIC WAVES, *ARMS CONTROL, *NUCLEAR EXPLOSION DETECTION, *EARTH MANTLE, SYMPOSIA, SURFACE WAVES, VERIFICATION, MONITORING, ELASTIC PROPERTIES, UNDERGROUND EXPLOSIONS, NUCLEAR EXPLOSION TESTING, WAVE PROPAGATION, SEISMIC DISCRIMINATION, TREATIES, SEISMIC VELOCITY, EURASIA, TRAVEL TIME, PHASE VELOCITY, LITHOSPHERE, WEST AFRICA, CHEBYSHEV POLYNOMIALS.

Subject Categories : Government and Political Science
      Geology, Geochemistry and Mineralogy
      Seismology
      Seismic Detection and Detectors
      Nuclear Weapons

Distribution Statement : APPROVED FOR PUBLIC RELEASE