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Volcanic gases are gases given off by active (or, at times, by dormant) volcanoes. These include gases trapped in cavities ( vesicles ) in volcanic rocks , dissolved or dissociated gases in magma and lava , or gases emanating from lava, from volcanic craters or vents.
The volcanic materials form a vertical column or plume that may rise many kilometers into the air above the vent of the volcano. In the most explosive eruptions, the eruption column may rise over 40 km (25 mi), penetrating the stratosphere. Stratospheric injection of aerosols by volcanoes is a major cause of short-term climate change.
A volcanic eruption is essentially the only natural way for short-lived – less than a few years – gases like sulfur dioxide and water vapor to make it into the stratosphere.
Gas-poor magmas end up cooling into rocks with small cavities, becoming vesicular lava. Gas-rich magmas cool to form rocks with cavities that nearly touch, with an average density less than that of water, forming pumice. Meanwhile, other material can be accelerated with the gas, becoming volcanic bombs. These can travel with so much energy that ...
(However, in the case of the eruption of Mount St. Helens, the pressure was released on the side of the volcano, rather than the crater. [3]). The release of pressure causes more gas to exsolve, doing so explosively. The gas may expand at hundreds of metres per second, expanding upward and outward.
The first helicopter overflight of Kīlauea's new SW rift zone eruption site at 6 AM HST on June 3, 2024 showed lava fountaining from 1 km (0.5 mi)-long fissures and volcanic gases blowing downwind.
It can be caused by magma withdrawal (related to intrusion or eruption), volatile escape, thermal contraction, phase changes during crystallization, and tectonic extension. [2] Deformation is a key indicator of pre-eruptive unrest at many active volcanoes, but deformation signals must be used in combination with other eruption indicators for ...
Super volcano is the term used to describe volcanoes that have gradually over time built up immense amounts of magma and could wreak havoc if ejected onto the planet's surface. And in the heart of ...