Its powerful jet of steam ejects the column of water above it. The water rushes through the tube and into the air. The eruption will continue until all the water is forced out of the tube, or until the temperature inside the geyser drops below boiling (100 degrees Celsius, or 212 degrees Fahrenheit, at sea level).

When a geyser "explodes," it is typically a hydrothermal explosion, which differs from a standard eruption. In a normal eruption, water is superheated by magma and turned into steam, which forces the water above it out through a vent. However, if the vent becomes clogged or the pressure drops suddenly, the superheated water instantly flashes into steam in a violent expansion. This can shatter surrounding rock, creating a crater and throwing debris (mud, boiling water, and jagged stones) hundreds of feet into the air. These events are unpredictable and extremely dangerous because they can occur without the usual rhythmic warning signs of a standard geyser. In 2024, a notable hydrothermal explosion at "Black Diamond Pool" in Yellowstone served as a reminder of this power; while no one was injured, the force was enough to destroy the surrounding boardwalk and permanently alter the shape of the thermal feature by ejecting large quantities of ancient silica and rock.