GEOLOGY

Detailed explanation-1: -A geyser forms when hot water and steam are trapped underground in a narrow crack. Pressure builds up until the hot water and steam erupt from the ground. This happens over and over again. Old Faithful is a geyser in Yellowstone National Park.

Detailed explanation-2: -Subsurface magma heats groundwater, creating steam and hot water. The hot, less dense water rises through fissures and cracks in the ground. When it reaches the surface, features such as geysers, fumaroles, hot springs, and mud pits are created.

Detailed explanation-3: -"Phreatic” (or steam-blast) eruptions are driven by explosive expanding steam resulting from cold ground or surface water coming into contact with hot rock or magma.

Detailed explanation-4: -Fumaroles. Fumaroles are places where steam and volcanic gases are emitted. They are present on most active volcanoes. The occurrence of fumaroles and other geothermal features such as hot springs, geysers, and mud pots are important signs that a volcano is active.

Detailed explanation-5: -What makes a geyser erupt? Water percolating down from above is warmed by geothermal heat from below, forming pressurized steam in an underground cavity. The high pressure causes the water to become superheated above its usual boiling point of 212 degrees F (100 degrees C).