Lava dome

Definition

A lava dome is a mound-shaped volcanic feature created by the slow extrusion of viscous lava from a volcano, resulting in a dome-like structure. These formations are usually composed of andesitic, dacitic, or rhyolitic lava that is too thick to flow easily, causing it to pile up near the vent. Lava domes can grow over time, sometimes leading to explosive eruptions if pressure builds up underneath.

5 Must Know Facts For Your Next Test

1. Lava domes can vary significantly in size and shape, depending on the viscosity of the lava and the rate at which it is extruded.
2. These structures can be quite hazardous as they may collapse or produce explosive eruptions when gas pressure builds up within the dome.
3. Some well-known lava domes include Mount St. Helens' Lava Dome, which formed after the major eruption in 1980.
4. Lava domes often grow in stages, with periods of increased activity followed by pauses, allowing for complex growth patterns.
5. Unlike shield volcanoes that produce fluid lava flows, lava domes are associated with more viscous lava that creates steep-sided formations.

Review Questions

• How do lava domes differ from other volcanic structures in terms of lava viscosity and eruption style?
  • Lava domes differ from other volcanic structures primarily due to the viscosity of the lava they produce. While shield volcanoes typically generate low-viscosity basaltic lava that flows easily over large distances, lava domes are formed from more viscous andesitic, dacitic, or rhyolitic lava that cannot flow far. This difference in lava behavior results in distinct shapes; while shield volcanoes have broad, gentle slopes, lava domes are characterized by steep-sided, mound-like formations.
• What factors contribute to the potential hazards associated with lava domes during volcanic eruptions?
  • The hazards posed by lava domes during volcanic eruptions stem from their growth patterns and the nature of the lava involved. As a lava dome builds up over time, gas pressure can accumulate within it. If this pressure exceeds the strength of the dome material, it can lead to sudden collapses or explosive eruptions that release pyroclastic flows. Additionally, because lava domes are often situated near populated areas, their potential for explosive behavior makes them particularly dangerous.
• Evaluate the role of monitoring techniques in predicting the activity of lava domes and minimizing risks to surrounding communities.
  • Monitoring techniques play a crucial role in predicting lava dome activity and mitigating risks to nearby communities. By employing methods such as seismology, gas emission analysis, and satellite imaging, scientists can track changes in volcanic behavior and identify signs of increased pressure or impending eruptions. These observations enable authorities to issue timely warnings and implement evacuation plans when necessary. Effective monitoring not only helps protect lives but also contributes to understanding the geological processes behind lava dome formation and eruption dynamics.

Related terms

Volcanic eruption: The process by which volcanic materials, including lava, ash, and gases, are expelled from a volcano during an explosive or effusive event.

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

Caldera:

A large depression formed when a volcano erupts and collapses into itself, often resulting in a massive crater that can fill with water to form a lake.