Lava fountain

Definition

A lava fountain is a spectacular eruption phenomenon where molten rock is explosively ejected from a volcano, forming high jets or sprays of lava that can reach impressive heights. These fountains result from gas buildup in the magma that creates pressure, which, when released, propels the lava into the air. The dynamics of lava fountains play a significant role in understanding different eruption styles and assessing potential hazards associated with volcanic activity.

5 Must Know Facts For Your Next Test

1. Lava fountains typically occur during highly explosive eruptions, where gases dissolved in the magma create pressure that results in violent ejections of lava.
2. The height of lava fountains can vary significantly, sometimes reaching over 100 meters (328 feet) depending on the eruption's intensity and gas content.
3. Lava fountains are often associated with basaltic magma, which has lower viscosity, allowing for easier gas escape and explosive eruptions.
4. These fountains can lead to the formation of scoria cones, small volcanic hills created from the accumulation of eruptive material around the vent.
5. Monitoring lava fountains is crucial for assessing volcanic hazards as they can indicate changes in a volcano's behavior and provide warnings for nearby communities.

Review Questions

• How do gas dynamics within magma influence the formation of lava fountains during eruptions?
  • Gas dynamics play a critical role in the formation of lava fountains. As magma rises toward the surface, dissolved gases begin to expand due to decreasing pressure. This buildup of gas increases pressure until it exceeds the strength of the surrounding magma, leading to explosive eruptions. When this pressure is released suddenly, it results in the dramatic ejection of lava as a fountain. Thus, understanding gas content and behavior in magma is essential for predicting such eruptive phenomena.
• Discuss how lava fountains contribute to our understanding of different eruption styles and their classification.
  • Lava fountains are a key feature in classifying eruption styles due to their explosive nature and visual impact. They signify a transition from effusive eruptions, characterized by flowing lava, to more explosive types where rapid gas expansion drives the eruption. By studying lava fountains, volcanologists can differentiate between types of eruptions, assess potential hazards associated with each style, and develop models to predict future volcanic activity. This classification helps guide preparedness efforts for communities at risk.
• Evaluate the potential hazards posed by lava fountains and how monitoring them can mitigate risks to nearby populations.
  • Lava fountains pose several hazards, including the possibility of falling tephra, pyroclastic flows, and lava flows that can threaten lives and property. The height and intensity of these fountains can also lead to ash dispersal over large areas. By monitoring volcanoes for signs of increased activity that could indicate an imminent fountain event, scientists can provide timely warnings to affected communities. This proactive approach allows residents to evacuate or take necessary precautions, ultimately reducing risks associated with volcanic eruptions.

Related terms

pyroclastic flow: A fast-moving current of hot gas and volcanic matter that flows down the slopes of a volcano, often resulting from explosive eruptions.

vent: An opening in the Earth's crust through which volcanic materials, including gases and lava, escape during an eruption.

tephra: Fragments of volcanic rock and ash that are ejected during an explosive eruption and can vary in size from tiny ash particles to large volcanic bombs.