PEKERIS, CHAIM LEIB (1908–1993), mathematician. Born in Alytus, Lithuania, Pekeris immigrated to the United States in his late teens. He did research at the Massachusetts Institute of Technology from 1936 to 1940, and from 1941 to 1946 headed the mathematics-physics group in the war research division at Columbia University. After two years at the Institute for Advanced Study at Princeton, he went to Israel in 1948, to establish the department of applied mathematics at the Weizmann Institute of Science. Under his direction, an eight-year gravimetrical and seismic mapping survey of the country was undertaken, and methods of prospecting were developed which laid the basis for Israel's petroleum-boring programs.
Pekeris' own main interests were the internal constitution of the earth, including the study of the origin and nature of earthquakes, theoretical seismology, the calculation of ocean tides, and the way fluids flow through pipes and around obstacles.