UTIG RESEARCH PROJECTS ARCHIVEAnisotropic Earth Model Calculations
Principal Investigator: Mrinal K. Sen Funded by: Texas Higher Education Coordinating Board Most of what we know today about the Earth's interior has been derived from Seismology.
The seismograms from earthquakes recorded at stations all over the world are analyzed to
derive compressional and shear wave velocity and density as a function of depth. In
laboratory experiments, rocks and minerals are subjected to high pressure and temperature
simulating conditions in the earth's deep interior. These data are used in conjunction
with seismological data to infer the chemical composition of the materials in the earth's
interior. Most of these calculations have been done assuming very simple earth models such
as a 1D isotropic earth. Attempts have been made recently to derive three dimensional earth models using a
technique called tomography that uses only the travel time data. Some efforts have been
made using long period waveform data of surface waves. Nonetheless widespread observations
of anisotropic propagation effects on seismic observations have recently been reported. Of
particular importance are anisotropic behavior of the upper mantle, the core-mantle
transition zone, and the inner core. In all of these observations inference has been drawn
based on qualitative analysis of travel time anomalies and splitting of shear waves. No
attempt has been made to apply forward modeling of the observed seismograms. Efficient
algorithms for such calculations do not readily exist. We propose to develop algorithms for the calculation of synthetic seismograms for anisotropic Earth models in spherical coordinates. These will be used to derive constraints on the anisotropic parameters of Earth's deep interior. Our result will enable the Earth science community to either validate the existing models of the mantle and inner core, or allow us to derive new models. Such results will have far reaching implications in terms of chemical composition of materials, global tectonics, mantle convection and the generation of Earth's magnetic field. |