VOLCANIC
A volcanic eruption is a violent emission in the terrestrial surface or of another planet, of matters proceeding from the interior of the globe. Exempting the geysers, which issue warm water, and the volcanoes of mud which matter, largely organic, comes from deposits of hydrocarbons relatively near to the surface, the terrestrial eruptions owe to the volcanoes.
The volcanic eruptions do not obey any law of periodicity, and it has not been possible to discover a method to foresee them, though sometimes they come preceded by seismic jolts and by the emission of fumaroles. His violence is in relation with the acidity of the lava and with the content of these in gases oclusos.