Studies of Global Seismicity and Earth's Structure

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DziewonskiEAR-0207608The principal objectives of this project are the systematic investigation of global seismicity and the three-dimensional mapping of the Earth's interior. The earthquake studies are focused around the Harvard CMT project. All earthquakes with magnitudes greater than approximately 5.2 are analyzed for their source mechanisms using digital data from globally distributed seismographs. Unusual seismic phenomena, such as slow earthquakes, volcanic collapses, and unidentified seismic signals, are investigated in detail. Results are disseminated using electronic mail and the Harvard Seismology web page: http://www.seismology.harvard.edu. The imaging of the elastic properties of the Earth's interior is pursued by development of new data sets and the joint inversion of various existing data sets, such as absolute and differential travel times, surface-wave dispersion curves, full waveforms, and normal-mode spectra. Particular consideration is given to the inclusion of anisotropy (radial, azimuthal, and general) in the model parameterization and inversion. Models and derived data sets are available on the investigators' web site.--