Phreatic eruption
Phreatic eruptions are steam-driven explosions that occur when water beneath the ground or on the surface is heated by magma, lava, tephra or pyroclastic-flow deposits. The intense heat of such material causes water to flash to steam, thereby generating an explosive eruption.
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Craters formed by phreatic explosions when lava flows entered Lake Myvatn, northern Iceland. Photo: J. Alean |