Phreatic Eruptions

Fourpeaked Volcano eruption, September 17, 2006. Katmai National Park and Preserve, Alaska

Photograph by Lanny Simpson, Alaska High Mountain Images.

Introduction

Eruptions that are driven by steam explosions due to the superheating of groundwater by a magmatic source. Phreatic eruptions may include volcanic ash made of shattered rock material, but incorporate no magmatic (e.g., juvenile) material.

The 2006 phreatic eruption of Fourpeaked Volcano in Katmai National Park and Preserve sent an ash cloud 20,000 feet (6,100 m) into the atmosphere.

Phreatic eruptions may be precursors to magmatic eruptions.

Related Links

• NPS Volcanoes—Eruption Classifications

• Katmai National Park and Preserve (KATM), Alaska—[KATM Geodiversity Atlas] [KATM Park Home] [KATM Volcanoes] [KATM npshistory.com]

• USGS Alaska Volcano Observatory—Novarupta (in Katmai National Park and Preserve)

Volcanoes, Craters, and Lava Flows