Revolutionizing Earth Science: How Seismic Surveys Unveil the Earth’s Hidden Structure

Through so-called seismic surveys, geologists can create a complete picture of the earth’s structure.

Sound waves are sent down into the ground, and by measuring the sound signals that are thrown back, geologists can work out what material the sound waves encounter on the way.

In addition, the researchers can use special instruments, called seismographs, to measure how fast earthquake waves, P and S waves, propagate in the interior of the earth. In this way, they can measure the density of the different layers of the soil and find out what they are.

The Danish geophysicist Inge Lehmann used this method in 1936, when she concluded that the Earth’s core must have two parts: a solid inner part in the middle, surrounded by an outer mantle liquid

The combination of these methods is used to create a type of three-dimensional X-ray image, which instead of the muscles and tendons of the body shows the layers and rocks of the planet.