Lava domes

Definition

Lava domes are mound-shaped protrusions formed by the slow eruption of viscous lava that piles up near a volcanic vent. These formations are typically made from andesitic, dacitic, or rhyolitic lava, which is thicker and cooler than basaltic lava, causing it to flow less freely. Lava domes can grow over time, often becoming quite large and steep-sided, and they are associated with explosive volcanic activity.

5 Must Know Facts For Your Next Test

1. Lava domes can vary in size from a few meters to several hundred meters in diameter and height, depending on the volume and viscosity of the erupted lava.
2. These structures are often unstable and can collapse or produce pyroclastic flows if they grow too large or experience sudden changes in pressure.
3. The surface of a lava dome can exhibit various textures, including smooth, blocky, or shattered appearances due to the cooling and solidification process.
4. Some famous lava domes include Novarupta's Lava Dome in Alaska and Mount St. Helens' Lava Dome in Washington State, which formed after significant eruptions.
5. Lava domes may also be accompanied by other volcanic features like craters and fissures, contributing to their complex geological landscape.

Review Questions

• How do lava domes differ from other volcanic structures such as shield volcanoes or stratovolcanoes?
  • Lava domes differ from shield volcanoes and stratovolcanoes primarily in their shape and eruption style. While shield volcanoes are broad with gentle slopes formed by low-viscosity basaltic lava, lava domes are steep-sided and formed from thick, viscous lava that piles up close to the vent. Stratovolcanoes have layered structures formed from alternating eruptions of lava and tephra. Lava domes can also indicate more explosive volcanic behavior compared to the generally effusive eruptions of shield volcanoes.
• Discuss the potential hazards associated with lava dome formation during volcanic eruptions.
  • Lava dome formation poses several hazards, including the risk of dome collapse, which can generate pyroclastic flows that are extremely dangerous due to their speed and temperature. Additionally, as lava domes grow, they may become unstable, leading to explosive eruptions that can eject tephra and gas into the atmosphere. These hazards make monitoring lava domes crucial for assessing volcanic activity and protecting nearby communities from potential disasters.
• Evaluate the role of lava domes in understanding volcanic processes and predicting future eruptions.
  • Lava domes play a significant role in understanding volcanic processes because their formation provides insights into the behavior of magma beneath the Earth's surface. By studying the growth patterns, composition, and collapse events of lava domes, scientists can better predict future eruptions and assess volcanic risks. This knowledge helps inform evacuation plans and hazard mitigation strategies for communities living near active volcanoes. Additionally, monitoring changes in dome shape and gas emissions can indicate potential shifts in eruptive activity.

Related terms

volcano:

A geological structure that forms when molten rock, ash, and gases escape from a magma chamber beneath the Earth's surface.

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

tephra: Fragmental material produced by a volcanic eruption, including ash, pumice, and larger rocks ejected during explosive events.