Ewing was 1944-1949 Associate Professor, 1947-1959 Professor and from 1959 to 1972 Higgins Professor of Geology at Columbia University. At his suggestion, the Lamont - Doherty Earth Observatory was founded in 1949.
Ewing made important contributions to geophysics. In particular, he examined the processes involved in the deposition on the sea floor and on land. Ewing also worked on topics in seismology, earthquake research and contributed for the detection of underground explosions, to underwater acoustics and for sedimentology and tectonics.
Ewing analyzed and pointed a large part of the seismic spectrum of seismic waves, the so-called coda. He examined the free oscillations of the earth, the sound channel of the ocean and the dispersion of sound in sea water.
Ewing suggested the use of the SOFAR channel for locating downed pilots over the sea. He improved or constructed including the Bathythermographen, sonar, hydrophones, equipment for gravimetry and underwater cameras.
William Maurice Ewing in 1957 for his outstanding research with the highest award of the American Geophysical Union, the William Bowie Medal honored. He also received in 1964 the Gold Medal of the Royal Astronomical Society, and in 1974 the Penrose Medal of the Geological Society of America. According to him even the Maurice Ewing Medal is named, which is awarded by the American Geophysical Union since 1976.
Ewing died on 4 May 1974 in Galveston, Texas, and was in Palisades, New York State, buried.