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Inge Lehmann
1888–1993 · Seismology and geophysics
Danish seismologist Inge Lehmann detected clues in earthquake waves that led her to identify Earth's inner core, changing our picture of the planet.
Why is this scientist famous?
Used earthquake waves to infer that Earth has a distinct inner core inside its liquid outer core.
Seismologists still use earthquake waves to map structures inside Earth.
Inge's story
Questions beneath our feet
Inge Lehmann was born in Copenhagen, Denmark, in 1888. She studied mathematics and developed a career investigating earthquakes. Most people cannot see far beneath Earth's surface, but seismologists measure vibrations from earthquakes to study the deep planet. Lehmann became skilled at interpreting faint signals recorded by instruments far from an earthquake.
A puzzle in the waves
Some earthquake waves reached places where older models predicted they should be absent. Rather than dismissing the strange signals as errors, Lehmann examined how waves could change direction deep inside Earth. Her 1936 paper proposed a boundary around a separate inner core. It offered an explanation for arrivals of earthquake waves in the so-called shadow zone.
A new picture of Earth
Scientists now understand that Earth has a solid inner core surrounded by a liquid outer core. Lehmann's model helped transform the scientific picture of the planet's interior. Her conclusion was based on indirect evidence, not on anyone drilling down to the core. Later measurements and developments in seismology strengthened the evidence for this structure.
A long scientific life
Lehmann continued to work on seismic waves for decades and contributed to studies of Earth's interior. She earned major scientific recognition, including the William Bowie Medal in 1971. She died in 1993 at the age of 104. Her discoveries remind us that information about hidden places can be recovered from the careful study of waves.
What did they discover?
Earth's inner core
Explained puzzling earthquake-wave arrivals by proposing an inner core separated from the outer core.
Interpreting earthquake-wave records
Used seismic-wave travel patterns to infer structures deep inside Earth.
Deep-Earth seismology
Contributed to the use of seismology as a method for understanding planetary interiors.
Amazing facts
She was educated at a school noted for treating girls and boys equally.
Her main discovery came from earthquake-wave records rather than drilling.
The key scientific paper appeared in 1936.
A wave shadow zone was central to the scientific puzzle she studied.
She worked in a scientific field that included very few women at senior levels.
The boundary around the inner core is associated with her name.
She received the William Bowie Medal in 1971.
She lived to the age of 104.
Timeline
Born in Copenhagen, Denmark.
Became head of the seismological department at the Danish Geodetic Institute.
Published a paper proposing a distinct inner core.
Received the William Bowie Medal.
Died in Copenhagen, Denmark.