A gas slug is one of a number of high pressure bubbles of gas that rise from deep within some volcanoes to eventually explode at the surface in an eruption of magma. These bubbles are one of the main forces behind Strombolian eruptions. The gas slug typically bursts when it comes into contact with the air and creates the distinct Strombolian lava arc. The bubbles can sometimes form miles beneath the surface and rise faster than the magma in which they form. Volcanologists are still unsure how these gas slugs form.
Volcanology is the scientific study of volcanoes, and a volcanologist studies how volcanoes develop. They often travel to eruptions to gather samples of ash, rock and lava to further understand the inner mechanisms of the volcano. One of their main aims is to hopefully one day predict when and where another eruption might take place, and so save human lives. They also seek to find out more about the formation of the Earth.
The name “Stromboli” comes from Mt. Stromboli. This volcano has been erupting almost without stopping for 20,000 years. This particular type of explosion is gas-driven and typically erupts roughly every few minutes at intermittent intervals. A gas slug can sometimes cause the lava to spew and arc hundreds of feet into the air. The Strombolian volcano is often fed by pools of lava that can build up in the channels of the volcano and they tend to be the least violent of eruptions.
A gas slug within the magma can create a number of different types of eruption. They can explode in a spattering fashion or with solidified chunks of glassy textured lava. Scoria, which is lava that still has gas bubbles within its hardened form, and lava flows are other types of end product from the gas slugs. Lava flows occur when melted streams of lava join together and begin to flown down the outer sides of the volcano. The name for all of these forms of explosive material is sometime referred to as “tephra.”
Volcanic gases are actually dissolved within molten rock at depth, but once the magma reaches a point where the pressure is sufficiently low, the gas begins to form bubbles. This in turn allows the magma to more easily continue its flow to the surface. Eventually magma and gas slug reach the surface with a series of explosions and lava arcs.