What is Seismology?

Seismology is the study of earthquakes and seismic waves that move through and around the Earth. A seismologist is a scientist who studies earthquakes and seismic waves.

What are Seismic Waves?

Seismic waves are caused by the sudden movement of materials  within the Earth, such as slip along a fault during an earthquake. Volcanic eruptions, explosions, landslides, avalanches, and even rushing rivers can also cause seismic waves. Seismic waves travel through and around the Earth and can be recorded with seismometers.

Types of Seismic Waves

There are several different kinds of seismic waves, and they all move in different ways. The two main types of waves are body waves and surface waves. Body waves can travel through the Earth's inner layers, but surface waves can only move along the surface of the planet like ripples on water. Earthquakes send out seismic energy as body waves (P and S). When body waves reach the surface, some of that energy is converted to surface waves.

Small P-wave oscillations on the left and larger amplitude S-wave oscillations on the right.
The body waves (P and S) and surface waves recorded by a seismometer.

Body Waves