Lava

Definition

Lava is molten rock that erupts from a volcano and flows onto the Earth's surface, cooling and solidifying to form igneous rock. Its characteristics, such as viscosity and temperature, greatly influence volcanic processes, eruption styles, and the types of volcanic products that result from eruptions.

5 Must Know Facts For Your Next Test

1. Lava can be classified into different types based on its composition, such as basaltic, andesitic, and rhyolitic lava, each having distinct properties.
2. The temperature of lava ranges from about 700 to 1,200 degrees Celsius (1,300 to 2,200 degrees Fahrenheit), affecting its flow behavior.
3. Low-viscosity lava flows easily and can travel long distances, while high-viscosity lava tends to pile up near the vent, creating steep-sided lava domes.
4. Lava can produce various volcanic landforms, including shield volcanoes from low-viscosity flows and stratovolcanoes from more viscous eruptions.
5. When lava cools rapidly upon contact with water or air, it can form unique textures and structures like obsidian or pillow lava.

Review Questions

• How does the viscosity of lava affect its flow and the resulting landforms created during a volcanic eruption?
  • The viscosity of lava plays a crucial role in determining how it flows and the types of landforms that are created. Low-viscosity lava can flow smoothly and spread over large areas, leading to the formation of broad shield volcanoes. In contrast, high-viscosity lava tends to move more slowly and can create steep-sided structures like lava domes. Thus, understanding lava viscosity helps in predicting eruption styles and landscape changes.
• Discuss the relationship between magma composition and the types of lava produced during volcanic eruptions.
  • The composition of magma is a key factor in determining the type of lava that erupts. Basaltic magma, which has lower silica content, produces low-viscosity basaltic lava that flows easily. Conversely, more silica-rich magmas, like andesitic or rhyolitic magma, result in higher-viscosity lavas that are less fluid. This composition not only influences the behavior of the eruption but also affects the resulting volcanic landforms and products.
• Evaluate how different types of lava contribute to the variety of volcanic products observed across different volcanoes.
  • Different types of lava contribute significantly to the diversity of volcanic products through their unique physical and chemical characteristics. Basaltic lavas typically lead to fluid flows that create extensive shield volcanoes and are often associated with features like pahoehoe and aa. In contrast, more viscous lavas from stratovolcanoes tend to produce explosive eruptions resulting in ash, pumice, and other pyroclastic materials. By analyzing these variations in lava types, we can better understand the geological evolution of different volcanic regions and their potential hazards.

Related terms

Magma: Magma is molten rock located beneath the Earth's surface, which can rise to the surface during volcanic eruptions and become lava.

Viscosity:

Viscosity refers to a fluid's resistance to flow, which affects how lava moves and spreads during an eruption.

Pahoehoe: Pahoehoe is a type of lava flow that is smooth and ropy in texture, often associated with low-viscosity basaltic lava.