Lava

Definition

Lava is molten rock that erupts onto the Earth's surface during a volcanic eruption. Once it flows out of a volcano, lava can vary in composition, temperature, and viscosity, influencing the type of eruption and the landscape it creates. The properties of lava directly affect volcanic processes, such as whether an eruption is explosive or effusive, and how lava solidifies into different landforms like lava tubes or basalt plateaus.

5 Must Know Facts For Your Next Test

1. Lava temperature can range from about 700°C to 1,200°C (1,292°F to 2,192°F), affecting its viscosity and flow behavior.
2. There are two main types of lava: basaltic lava, which is low in viscosity and flows easily, and rhyolitic lava, which is more viscous and can lead to explosive eruptions.
3. When lava cools rapidly upon contact with water or air, it can create unique formations such as pillow lavas or obsidian.
4. The composition of lava plays a significant role in determining the type of volcano; shield volcanoes typically produce low-viscosity basaltic lava, while stratovolcanoes may erupt more viscous and explosive materials.
5. Lava flow rates can vary greatly; some flows can advance at a few meters per day while others may move much faster under certain conditions.

Review Questions

• How do the properties of lava influence the type of volcanic eruption that occurs?
  • The properties of lava, including its composition, temperature, and viscosity, significantly influence the style of volcanic eruptions. Low-viscosity basaltic lava allows for gentle, effusive eruptions that create broad shield volcanoes. In contrast, high-viscosity rhyolitic lava can trap gases until pressure builds up enough to cause explosive eruptions, typical of stratovolcanoes. Thus, understanding lava properties is key to predicting eruption behaviors.
• Discuss the role of volcanic gases in relation to lava during an eruption.
  • Volcanic gases play a critical role in shaping the dynamics of lava during an eruption. As magma rises to the surface and pressure decreases, gases dissolved in the magma expand and escape. This release can increase the pressure within the magma chamber and influence whether the eruption will be explosive or effusive. For instance, high gas content in more viscous lava leads to explosive eruptions that eject tephra into the atmosphere.
• Evaluate the environmental impacts of lava flows on surrounding ecosystems during and after a volcanic eruption.
  • Lava flows can have profound effects on surrounding ecosystems both during and after a volcanic eruption. During an eruption, flowing lava can destroy vegetation, alter landscapes, and disrupt wildlife habitats. However, once cooled and solidified, these new landforms create unique habitats for pioneering species. Over time, ecosystems may recover through succession processes as life gradually reestablishes itself on the newly formed terrain. Therefore, while initially destructive, lava flows also contribute to long-term ecological development.

Related terms

Magma: Magma is the molten rock located beneath the Earth's surface, which can rise to form lava during a volcanic eruption.

Volcanic Gas: Volcanic gases are gases released during volcanic eruptions, which can influence the behavior of lava and the explosiveness of an eruption.

Tephra: Tephra refers to fragmented volcanic material ejected during an eruption, which can include ash, pumice, and larger volcanic rocks.