Inge Lehmann

Inge Lehmann was a Danish seismologist who proposed in 1936 that Earth has a solid inner core, using seismic-wave observations to infer its existence.

Earth's inner core: Earth’s innermost layer is a solid sphere composed mainly of iron and nickel. Lehmann’s analysis established the inner core as a distinct solid region.
P-wave: A P-wave is a compressional seismic wave that travels through solids and fluids. Lehmann interpreted unexpected P-wave arrivals as evidence for a boundary within the core.
P′ (1936): P′ is Inge Lehmann’s 1936 paper proposing a solid inner core from anomalous seismic-wave arrivals. This paper presented the inference that established her scientific reputation.
Harold Jeffreys: Harold Jeffreys was a British mathematician and geophysicist who developed influential models of Earth’s interior. His earlier account of the core’s seismic shadow zones framed the problem Lehmann solved.
PKiKP wave: PKiKP is a seismic compressional wave that reflects from the boundary between Earth’s inner and outer core. This wave provides a direct way to investigate the boundary Lehmann inferred.
Earth's core: Earth’s central region consists of a liquid outer core surrounding a solid inner core. Her discovery refined the structure of the core beyond its previously known liquid region.
Seismic wave shadow zone: A seismic wave shadow zone is a region where direct earthquake waves are absent because of refraction or reflection inside Earth. The core’s shadow-zone patterns supplied the observations her inner-core model explained.
Denmark: Denmark is a Nordic country in northern Europe and the birthplace of Inge Lehmann. Lehmann was Danish, and her scientific career began in its research institutions.
Beno Gutenberg: Beno Gutenberg was a German-American seismologist who measured the depth of Earth’s core-mantle boundary. His core-boundary findings supplied essential context for interpreting Lehmann’s wave observations.
Inner-core anisotropy: Inner-core anisotropy is the direction-dependent speed of seismic waves through Earth’s solid inner core. Its discovery added detail to the solid inner-core structure Lehmann established.

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