Basaltic lava

Definition

Basaltic lava is a low-viscosity, fluid lava that primarily contains basalt, a dark volcanic rock rich in iron and magnesium. This type of lava is typically produced during effusive eruptions, where magma rises to the surface and flows out gently rather than violently exploding. Due to its low viscosity, basaltic lava can travel great distances from the eruption site, contributing to the formation of extensive lava fields and shield volcanoes.

5 Must Know Facts For Your Next Test

1. Basaltic lava has a temperature range of about 1,100°C to 1,200°C (2,012°F to 2,192°F), allowing it to flow easily.
2. The low viscosity of basaltic lava means it can create large, broad landforms like shield volcanoes due to its ability to spread over wide areas.
3. Basaltic lava is typically associated with divergent plate boundaries and hotspots, where tectonic plates are pulling apart or where magma rises from deep within the Earth.
4. When basaltic lava cools, it can form various structures such as pahoehoe (smooth and ropy) and aa (rough and jagged) textures based on how it flowed and cooled.
5. The presence of gas bubbles in basaltic lava can lead to the formation of scoria, a light volcanic rock that can be produced during effusive eruptions.

Review Questions

• How does the composition of basaltic lava influence its behavior during volcanic eruptions?
  • The composition of basaltic lava, which is rich in iron and magnesium, leads to its low viscosity. This property allows the lava to flow more freely and cover large areas during effusive eruptions. Unlike more viscous lavas that can trap gases and lead to explosive eruptions, basaltic lava releases gases more easily as it flows, resulting in gentler volcanic activity and creating features such as shield volcanoes.
• Discuss the environmental impact of basaltic lava flows on the surrounding ecosystems during an effusive eruption.
  • Basaltic lava flows can significantly alter surrounding ecosystems by covering existing landforms with new rock material. The high temperatures can sterilize the ground beneath, destroying plant life and altering habitats for animals. However, over time, these areas may become fertile due to the minerals released as the basalt weathers, allowing new ecosystems to develop. The slow-moving nature of basaltic lava also gives animals time to escape compared to more explosive eruptions.
• Evaluate the role of basaltic lava in shaping geological features on Earth and its implications for understanding volcanic activity.
  • Basaltic lava plays a crucial role in shaping geological features such as shield volcanoes and extensive lava fields. Its ability to flow over great distances contributes to the creation of broad volcanic landforms that can dominate landscapes. Understanding the behavior of basaltic lava helps scientists predict future volcanic activity and assess hazards associated with effusive eruptions. By studying these patterns, researchers gain insights into tectonic processes and improve risk management strategies for communities near volcanoes.

Related terms

Magma: Magma is molten rock found beneath the Earth's surface, which can solidify to form igneous rock once it cools down.

Viscosity:

Viscosity refers to the thickness or resistance to flow of a fluid; in lava, lower viscosity allows it to flow more easily.

Effusive Eruption: An effusive eruption is a volcanic eruption characterized by the outpouring of lava onto the ground rather than explosive activity.