Phreatomagmatic (Hydrovolcanic) Eruptions

Explosive eruption column above Halema‘uma‘u Crater, Hawai’i on May 18, 1924.

Photo by K. Maehara, Public domain.

Introduction

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.

Learn More

• NPS—Maars and Tuff Rings

Devil Mountain Maar Lakes, Bering Land Bridge National Preserve, 2015.

NPS photo.

Crater Explosions

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.

At Kīlauea, when the lava column drops below the water table, groundwater may come into contact with with magma or hot rocks, causing violent steam explosions.

Swanson et al. 2011, public domain, USGS.

Related Links

• NPS Volcanoes—Eruption Classifications

• Bering Land Bridge National Preserve (BELA), Alaska—[BELA Geodiversity Atlas] [BELA Park Home] [BELA npshistory.com]

• Death Valley National Park (DEVA), California and Nevada—[DEVA Geodiversity Atlas] [DEVA Park Home] [DEVA npshistory.com]

• Hawaii Volcanoes National Park, Hawaii—[HAVO Geodiversity Atlas] [HAVO Park Home] [HAVO Eruptions] [HAVO npshistory.com]

• USGS Hawaiian Volcano Observatory—[Kīlauea] [Mauna Loa]

Volcanoes, Craters, and Lava Flows