Estimating seismic shear reflectivity from converted waves

Charles P. Ursenbach, Robert R. Stewart

A review is given of two theories relating shear-wave reflectivity to converted-wave reflectivity. Two new theories are also given for predicting shear reflectivity from converted-waves, which are found in Equations (5) and (7) of this paper. The four theories are compared through extensive calculation, which show that Equation (7) is the most accurate for data in which there are no known relationships between earth parameter contrasts. Further calculations show that other theories are more accurate if the data is assumed to satisfy some other condition, such as Gardner's relationship. An expression is also put forward that expresses shear-wave reflectivity in terms of an AVO intercept and gradient from converted waves.