Measuring earthquakes

Measuring earthquakes

. When an earthquake occurs beneath the surface of the Earth, it becomes the focus of seismic waves that travel through the Earth. Seismometers on the surface of the Earth record the arrival of the waves, and locate the position of the boundaries between internal layers of different composition, density, pressure and temperature (Fig. 4.3). Seismic waves known as S, or shear and shake, waves cannot pass though a fluid, and are reflected by it. The reflected waves shown here mark the boundary of the Earth's liquid outer core.

Copyright 2010, Professor Kenneth R. Lang, Tufts University