|A geyser is a spring that intermittently ejects hot water and steam. Geysers are normally located near active volcanic areas, but the hydrogeological conditions that result in geysers are rare on Earth. A geyser forms when surface water seeps through porous rocks, till it contacts rocks heated by magma. The water is then heated till it boils and the hot and pressurized water rises and is then ejected out of the geyser's surface vent, emptying a reservoir. Once a geyser has ejected, the reservoir needs to refill before it can erupt again, giving rise to the intermitted character of the hydrothermal explosions.