George returned to Caltech as an assistant professor in 1945, where he remained the rest of his career. Although the retirement rules in place then required that he become professor emeritus in 1981, he remained technically active in the field of earthquake engineering for two more decades.
Professor Housner had an extraordinary range of accomplishments in research. Perhaps most notable was development of the response spectrum as a fundamental tool in earthquake-resistant analysis and design. He was the first to use statistical methods and techniques of random processes to characterize strong-motion accelerograms and to assess the probabilities of experiencing damaging shaking at a specific site in a given number of years. He was a leader in the development of instrumentation to measure strong ground shaking and building response and in the programs to deploy these instruments and analyze the resultant data. He also saw the need for research on the dynamic characteristics of structures, and with colleagues at Caltech led the effort to develop “shaking machines” with sufficient force and frequency control to excite large buildings, dams, and other structures to amplitudes large enough to determine accurately their natural frequencies and mode shapes. To help understand how large liquid storage tanks respond to earthquake motion, he produced now-classic papers on the dynamics of rocking and sloshing of these structures.
In other classic papers he elucidated the mechanics of the dynamic behavior of inverted pendulum structures and the bending vibrations of pipelines carrying flowing fluid. He also did some of the first studies of the nonlinear yielding response of structures to strong earthquake motion and the role of soil flexibility—the soil-structure interaction phenomenon—in the earthquake response of buildings. In the area of soils engineering, he authored a seminal study of the mechanism of sand blows, the minigeysers that often accompany major earthquakes when areas of saturated soils are shaken strongly.
George was a “real engineer” as well as a researcher, and his advice was sought on many important engineering