Inge Lehmann

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Inge Lehmann
Lnge Lehmann 01.jp.jpg
Born (1888-05-13)May 13, 1888
Copenhagen, Denmark
Died February 21, 1993(1993-02-21) (aged 104)
Copenhagen, Denmark [1]
Nationality Danish
Fields Seismology
Institutions Geodetical Institute of Denmark
Alma mater University of Copenhagen, University of Cambridge
Notable awards William Bowie Medal (1971)

Inge Lehmann ForMemRS (May 13, 1888 – February 21, 1993), was a Danish seismologist who discovered the Earth's inner core.[2][3] In 1936 she argued, correctly, that the Earth's core is not one single molten sphere, but that an inner core exists which has physical properties that are different from those of the outer core.

Early life and education[edit]

Inge Lehmann was born and grew up in Østerbro, a part of Copenhagen. She was the daughter of the experimental psychologist Alfred Georg Ludvik Lehmann (1858–1921). She received her school education at a pedagogically progressive high school led by Hanna Adler, an aunt of Niels Bohr.[4] [5] According to Lehmann, her father and Adler were the two most significant influences for her intellectual development. After having finished school, she studied, with some interruptions due to poor health, mathematics at the University of Copenhagen and University of Cambridge.[6] She continued her studies of mathematics in Cambridge from 1910-1911 at Newhan College. In 1911 Lehmann returned from Cambridge feeling exhausted from the work, so she decided to put studies aside for a while. Lehmann developed good computational skills from an actuary office she worked for a few years until she continued her studies at Copenhagen University in 1918. She completed the candidates magisterii degree in physical science and mathematics in two years. When she returned to Denmark in 1923 she accepted a position at Copenhagen University as an assistant to J.F. Steffensen, the professor or actuarial science.[7]

Career[edit]

After a few years of work in the insurance business she became an assistant to the geodesist Niels Erik Nørlund, who assigned her the task of setting up seismological observatories in Denmark and Greenland. The beginning of her interest in seismology dates back to this time. In 1928 she passed her exam in geodesy and accepted a position as state geodesist and head of the department of seismology at the Geodetical Institute of Denmark, which was led by Nørlund.

In a paper titled P', she was the first to interpret P wave arrivals which inexplicably appeared in the P wave shadow of the Earth's core as reflexions at an inner core.[8] This interpretation was adopted within two to three years by other leading seismologists of the time, such as Beno Gutenberg, Charles Richter, and Harold Jeffreys. The Second World War and the occupation of Denmark by the German army hampered Lehmann's work and her international contacts significantly during the following years.

In the last years until her retirement in 1953 the relations between her and other members of the Geodetical Institute deteriorated, partly probably because she had little patience with less competent colleagues. After 1953, Inge Lehmann moved to the USA for several years and collaborated with Maurice Ewing and Frank Press on investigations of the Earth's crust and upper mantle. During this work, she discovered another seismic discontinuity, which lies at depths between 190 and 250 km and is usually referred to as "Lehmann discontinuity" in honor of its discoverer. Francis Birch noted that the "Lehmann discontinuity was discovered through exacting scrutiny of seismic records by a master of a black art for which no amount of computerization is likely to be a complete substitute..."

Awards and honors[edit]

She received many honors for her outstanding scientific achievements, among them the Harry Oscar Wood Award (1960), the Emil Wiechert Medal (1964), the Gold Medal of the Danish Royal Society of Science and Letters (1965), the Tagea Brandt Rejselegat (1938 and 1967), the election as a Fellow of the Royal Society (1969),[9] the William Bowie Medal (1971, as the first woman), and the Medal of the Seismological Society of America (1977). She was awarded honorary doctorates from Columbia University in 1964 and from the University of Copenhagen in 1968 as well as numerous honorific memberships.

The asteroid 5632 was named Ingelehmann in her honor.

In Aventura, Florida, there is a stretch of U.S. 1 and a bridge named in her honor.

In 1997 the American Geophysical Union established the Inge Lehmann Medal to honor "outstanding contributions to the understanding of the structure, composition, and dynamics of the Earth’s mantle and core."

Key publications[edit]

  • Lehmann, Inge (1936): P'. Publications du Bureau Central Séismologique International A14(3), S.87-115

See also[edit]

References[edit]

  1. ^ "Lehmann, Inge". Encyclopedia.com. Retrieved 15 October 2013. 
  2. ^ "Lehmann; Inge (1888 - 1993)". The Royal Society. Retrieved 24 September 2013. 
  3. ^ Bolt, Bruce A. (January 1994). "Obituary: Inge Lehmann". Physics Today 47 (1): 61. Bibcode:1994PhT....47a..61B. doi:10.1063/1.2808386. 
  4. ^ "WiP: Herstory: Spotlight Scientist: Inge Lehmann". Purdue University. Retrieved 15 October 2013. 
  5. ^ Knopoff, Leon. "Lehmann, Inge". UCLA. Retrieved 15 October 2013. 
  6. ^ Bolt, Bruce. "Inge Lehmann". UCLA. Retrieved 15 October 2013. 
  7. ^ Gillispie, Charles. Complete dictionary of scientific biography. Detroit, Mich.: Charles Scribner's Sons. p. 234. 
  8. ^ Bolt, Bruce A. (1987). "50 years of studies on the inner core". EOS 68 (6): 73,80–81. 
  9. ^ Bolt, B. A. (1 November 1997). "Inge Lehmann. 13 May 1888–21 February 1993: Elected For.Mem.R.S. 1969". Biographical Memoirs of Fellows of the Royal Society 43: 287–301. doi:10.1098/rsbm.1997.0016. 

Bibliography[edit]