1. Research Civ. Engr., Research Group, Earthquake Engrg. and Vibrations Div., Soils and Pavements Lab., U.S. Army Engr. Waterways Experiment Station, Vicksburg, Miss
2. Research Civ. Engr., Geodynamics Branch, Earthquake Engrg. and Vibrations Div., Soils and Pavements Lab., U.S. Army Engr. Waterways Experiment Station, Vicksburg, Miss