Violently-explosive eruptions driven by steam explosions produced by the interaction of hot magma with surface water or shallow groundwater. Hydrovolcanic eruptions include tephra derived from juvenile magma.
These eruptions produce tephra and steam.
Tuff Rings and Maars
Hydrovolcanic eruptions build tuff rings and maars such as Ubehebe Craters, a group of maars in Death Valley National Park, and the Espenberg maars in Bering Land Bridge National Preserve.
They have also occurred in the summit of Kilauea in Hawai’i Volcanoes National Park, most recently in the May 1924 explosive eruption when the lava level in Halema’uma’u (the summit crater) dropped allowing interaction between magma and groundwater.