Keith Bullen (mathematician)

Keith Edward Bullen (1906 – 1976) was a New Zealand mathematician and seismologist known for his significant contributions to the understanding of the Earth's interior structure. He collaborated with Harold Jeffreys to develop the Jeffreys-Bullen travel time tables, which became the standard reference for locating earthquakes and studying seismic wave propagation through the Earth.

Bullen was born in Auckland, New Zealand, and received his early education there. He later studied at Cambridge University, where he earned his doctorate. Upon returning to New Zealand, he joined the faculty of the University of Auckland, eventually becoming Professor of Applied Mathematics.

His research focused primarily on seismology, specifically the analysis of seismic waves to infer the properties of the Earth's layers. The Jeffreys-Bullen tables, published in 1940, represented a major advancement in this field. They provided precise travel times for seismic waves through the Earth, taking into account the varying densities and compositions of different layers. These tables allowed seismologists to more accurately determine the location and depth of earthquakes.

Bullen also made notable contributions to the understanding of the Earth's density distribution. He developed mathematical models of the Earth's interior and proposed various hypotheses about the composition and properties of different layers, including the core-mantle boundary. He is credited with the identification of the Earth's inner core as a solid.

Bullen was a prolific writer and authored several influential books on seismology and geophysics, including "An Introduction to the Theory of Seismology" and "The Earth's Density." His work had a lasting impact on the field of geophysics and continues to be relevant today. He received numerous awards and honors for his contributions to science.