How does geophysics help scientists investigate Earth’s interior?

Geophysics is a major branch of the Earth sciences that applies the principles and methods of physics to study the Earth’s interior, which is rarely under direct observation. Because scientists cannot directly access the deep Earth, they rely on mathematical interpretations of physical measurements to draw conclusions about its structure and properties.1

Key methods used to investigate the interior include:

• Seismology: This is the primary method for determining deep structure. Scientists analyze seismic waves produced by earthquakes or artificial means. By measuring the travel times of these waves as they reflect or refract through different materials, researchers can infer density, velocity, and elastic parameters. Techniques like seismological tomography allow for three-dimensional imaging of internal anomalies.1234
• Gravimetry: Scientists measure the Earth’s gravitational field using gravimeters on land, at sea, and via artificial satellites to understand mass distribution.1
• Magnetometry: By measuring the geomagnetic field, researchers gain insights into the planet's core and crustal magnetization, helping to trace continental drift over geologic time.14