Uncovering the geologic structure beneath Earth’s surface is important for a variety of reasons, including identifying natural resources and studying earthquake hazards. Scientists image Earth’s subsurface by observing seismic waves that travel through our planet.
When an earthquake occurs, several types of waves radiate from the event’s source. P waves and S waves move through the interior, and Love and Rayleigh waves (known as “surface waves” or “normal modes”) move across Earth’s surface. The speeds at which these waves travel and how each type is scattered in the subsurface can reveal a wealth of different information about underground structure.
