The study of elastic (seismic) waves and how they are produced. Global seismology is the study of seismic waves from earthquakes (and to a lesser extent nuclear explosions), to investigate the structure of and processes within the Earth. In exploration seismology, artificially generated seismic waves are used in the search for resources (e.g. hydrocarbons, etc.) and the study of the Earth’s surface and near-surface. Planetary seismology is the use of seismic waves to investigate the structure of and processes within planets and natural satellites in the solar system.