Natural, artificial, or induced events that cause earthquakes. Natural mechanisms include rock falls and slides, spontaneous rock-bursts, volcanic explosions, and tectonic plate motions. Artificial and induced earthquakes can result from explosions (quarry blasts, pressure release below dam sites, nuclear bombs, etc.) or rock-bursts associated with pressure release due to mining, etc. Generally such stress releases are sudden, resulting in the release of seismic energy, but bradyseisms gradually release stress and thus do not result in an earthquake.