Knowra Phreatic eruption Phreatic eruption A volcanic explosion driven by heated groundwater turning rapidly to steam. It can eject fragmented pre-existing rock without bringing new magma to the surface.
Hydrothermal system : A circulation system in which heated water and gases move through rock, often near a magma body. The circulating water supplies the fluid that can be flashed into steam.
Phreatomagmatic eruption : A volcanic eruption caused by direct interaction between magma and external water. Unlike a purely phreatic blast, it fragments newly erupted magma.
Mount Ontake eruption : A sudden 2014 phreatic eruption of Mount Ontake in Japan that killed 63 people. Its abrupt onset at a popular summit shows the danger of small, magma-free explosions.
Volcano monitoring : The systematic measurement of seismic, geodetic, gas, thermal, and other signals to assess volcanic activity. Multiple monitoring streams can reveal changes in a hydrothermal system before an explosion.
Superheating : Heating a liquid above its boiling point without it immediately changing into vapor. Confined groundwater can become superheated before pressure release triggers rapid vaporization.
Magmatic eruption : A volcanic eruption in which magma reaches the surface and releases gases and volcanic material. Fresh magma is the defining ejecta in this contrast, not merely heated groundwater.
Whakaari / White Island eruption : A deadly 2019 phreatic eruption at Whakaari / White Island, an active volcano in New Zealand. The event illustrates how hydrothermal explosions can threaten people close to an active crater.
Volcanic seismicity : Earthquake and vibration activity generated by processes within or around a volcano. Changes in shallow seismic signals may track fluid movement or pressure buildup.
Steam explosion : An explosion caused when liquid water rapidly vaporizes and expands into steam. Rapid steam expansion is the immediate driver of a phreatic blast.
Geyser : A hot spring that intermittently ejects water and steam through a surface vent. Both involve pressurized heated water, but a geyser is a recurring hydrothermal discharge rather than a volcanic explosion.
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