INFO SHEET - Seismic waves - Seismic waves are waves that travel through or over the Earth. They are usually generated by movements of the Earth’s tectonic plates (earthquakes) but may also be caused by explosions, volcanoes and landslides. Studies of the different types of seismic waves can tell us much about the nature of the Earth’s structure.
A 3D seismic image of Japan's southeastern margin
Beautiful interpreted seismic line, Santos Basin, Brazil, by Chris Jackson (2012), GSA Bulletin.
Comparison of seismic images obtained before and after the earthquake.
"In a normal fault, the blocks are being pulled apart, so one block slides down the other." Caption from link