ABSTRACT REGIONALIZED EARTH MODELS FROM LINEAR PROGRAMMING METHODS

This study is concerned with the development of pos-sible models of the internal structure of the earth consistent with a given set of observed data. A two stage linear pro-gramming procedure was used together with an assumed para-meterization to obtain an explicit envelope of possible shear velocity and density values in the mantle and core. This envelope is determined separately for oceanic, shield, and tectonic.regions of the upper mantle. The data used in this study consist of the mass and moment of inertia of the earth, periods of free oscillations, including recently available overtones, regionalized phase and group velocities of Rayleigh waves, and phase velocities of Love waves. The results constrain the variations of density and shear velocity in the lower mantle to within about 1.5 % from the center of the envelope. The density just below the mantle-core boun-dary was found to lie between 9.79 and 9.86 grams/cc. A rigid core was needed to satisfy the overtone data with a shear velocity between 3.35 and 3.52 km/sec. The radius of the mantle-core boundary was found to lie between 3476.38 and 3486.42 kilometers. Excellent agreement with recent travel time studies of body waves was found for shear velo-city in the lower mantle and for the radius of the mantle-core boundary. Geophysical and petrological interpretations based on these results are discussed