The discovery of Earth Interior

Richard D. Oldham's Discovery of the Earth's Core

1906

Richard D. Oldham was an English seismologist, discovered the Earth's core while investigating the speed of earthquake waves as a function of their depth within the Earth. Oldham found that the speed of earthquake waves becomes faster with greater depth of penetration into the Earth.

Andrija Mohorovicic and the Mohorovicic Discontinuity

1909

Andrija Mohorovicic was a Croatian seismologist. Mohorovicic realized that the velocity of a seismic wave is related to the density of the material that it is moving through. The lower density material immediately beneath the surface is now commonly referred to as Earth's crust. The higher density material below the crust became known as Earth's mantle.

Beno Gutenberg

1913

Beno Gutenberg studied seismic waves. Gutenberg observed that at a certain depth beneath the Earth's surface, primary waves slowed down dramatically and secondary waves stopped entirely. Gutenberg discontinuity boundary between the mantle and the core is measured at approximately 1,800 miles below the Earth's surface

Inge Lehmann: Discoverer of the Earth's Inner Core

1929

Lehmann discovered the inner core of the earth