Inge Lehmann

Inge Lehmann was born on May 13, 1888, in Østerbro, Copenhagen. Educated at Hanna Adler's progressive co-educational school and the University of Copenhagen, she earned degrees in mathematics and became chief of the seismological department of the Geodætisk Institut in 1928.

Analyzing seismic shock waves from a 1929 New Zealand earthquake recorded by global seismographs, Lehmann noticed P-waves arriving within the shadow zone where they were expected to be blocked by the liquid core. In her famous 1936 paper succinctly titled P', she mathematically demonstrated that Earth possesses a solid metallic inner core that reflects seismic waves. She was awarded the William Bowie Medal in 1971, living to the extraordinary age of 104.