Lava dome

Definition

A lava dome is a steep-sided, mound-like volcanic structure formed by the slow extrusion of viscous lava, typically andesitic, dacitic, or rhyolitic in composition. These formations are created when the lava is too thick to flow far from the eruption site, leading to the accumulation of lava near the vent. Lava domes can be associated with explosive eruptions, and they often exhibit unique growth patterns and collapse features, making them significant in understanding volcanic processes.

5 Must Know Facts For Your Next Test

1. Lava domes are typically formed from lava with high viscosity, which leads to a slow buildup rather than extensive flows.
2. The growth of a lava dome can lead to significant hazards, including potential collapse or explosive activity as pressure builds beneath the dome.
3. Some famous lava domes include Mount St. Helens' Lava Dome and Novarupta's Lava Dome, both illustrating diverse eruption styles.
4. Lava domes can grow rapidly over short periods but may also take years to form fully, depending on the supply of lava and eruption dynamics.
5. The surface of a lava dome is often characterized by cracks and other deformation features that provide insight into its internal processes.

Review Questions

• How does the viscosity of lava contribute to the formation and characteristics of a lava dome?
  • The viscosity of lava is crucial in forming a lava dome because high-viscosity lavas do not flow easily. Instead of spreading out over long distances like low-viscosity lavas (such as basalt), these thicker lavas accumulate near the vent. This results in the steep-sided structure typical of lava domes. The slow extrusion allows for unique surface features and growth patterns that differ from other volcanic landforms.
• Discuss the potential hazards associated with lava domes and how they impact surrounding areas.
  • Lava domes can pose several hazards due to their tendency to collapse or erupt explosively as pressure builds within them. When a dome collapses, it can produce pyroclastic flows, which are fast-moving currents of hot gas and ash that can devastate nearby areas. Additionally, if the dome becomes destabilized, it may trigger secondary explosive events that can disperse ash and volcanic materials over large distances, affecting air quality and local ecosystems.
• Evaluate the role of lava domes in understanding volcanic behavior and predicting eruptions.
  • Studying lava domes is essential for understanding volcanic behavior because they often serve as indicators of underlying magmatic processes. Monitoring changes in size, shape, and surface activity can provide insights into the potential for future eruptions. By analyzing past dome formations and eruptions, scientists can develop models to predict how similar structures might behave in different tectonic settings or during various stages of volcanic activity. This information is vital for risk assessment and public safety measures in areas surrounding active volcanoes.

Related terms

Volcanic ash: Tiny fragments of rock and glass that are expelled during explosive volcanic eruptions, often forming a cloud that can travel long distances.

Pyroclastic flow: A fast-moving current of hot gas and volcanic matter that flows down the slopes of a volcano during an explosive eruption.

Basalt:

A dark, fine-grained volcanic rock that is primarily composed of plagioclase and pyroxene minerals, typically formed from low-viscosity lava flows.