Accession Number : ADP204456

Title :   The Influence of 3-D Structure on Seismic Wave Propagation at Regional and Teleseismic Distances,

Corporate Author : AUSTRALIAN NATIONAL UNIV CANBERRA RESEARCH SCHOOL OF EARTH SCIENCES

Personal Author(s) : Kennett, B. L.

PDF Url : ADP204456

Report Date : 14 AUG 1995

Pagination or Media Count : 7

Abstract : Three-dimensional heterogeneity is pervasive in the Earth on a wide variety of scales. The aim of this project is to improve understanding of the influence of lateral variations in structure in the upper mantle on wave propagation at regional to far-regional and teleseismic distances. At regional scales we have investigated how to map the seismic velocity structure of a region exploiting records from natural events as a model for upgrading the knowledge base for verification studies. The primary focus of this aspect of the work is on the use of waveform inversion for surface waves (including higher modes) to determine three-dimensional shear wave structure, but receiver function studies of crustal structure and P wave tomography can be achieved with the same data. A set of deployments of portable broadband instruments in Australia have demonstrated how detailed knowledge of crustal and lithospheric structure can be built up by combining specific experiments (of about 6 months duration) with information available from permanent seismic stations. For global studies we have parametrized heterogeneous structures using a flexible interpolation scheme based on Delaunay tetrahedra. This approach is being applied to the construction of regionalized models of the upper mantle by inversion of travel times from selected events. The resultant three-dimensional model will be suitable for the prediction of wave propagation characteristics,such as travel time corrections for a wide range of seismic phases. These studies are designed to contribute to the support of a verification regime for a CTBT by providing improved knowledge of regional structure in different tectonic environments and developing representations of 3-D structure which can be used to aid in, for example, improved event location and characterization.

Descriptors :   *SEISMIC DETECTION, *SEISMIC WAVES, *ARMS CONTROL, *NUCLEAR EXPLOSION DETECTION, *EARTH MANTLE, SYMPOSIA, SURFACE WAVES, VERIFICATION, MONITORING, THREE DIMENSIONAL, WAVE PROPAGATION, EARTH CRUST, HETEROGENEITY, KNOWLEDGE BASED SYSTEMS, SEISMIC DISCRIMINATION, TREATIES, AUSTRALIA, SEISMIC VELOCITY, TRAVEL TIME, PRIMARY WAVES(SEISMIC WAVES), ELASTIC WAVES, SEISMIC ARRAYS, TECTONICS, SEISMOLOGICAL STATIONS, LITHOSPHERE.

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

Distribution Statement : APPROVED FOR PUBLIC RELEASE