Shield Volcanoes

Definition

Shield volcanoes are large, broad, and gently sloping volcanic structures formed primarily by the eruption of low-viscosity basaltic lava that can flow over great distances. These types of volcanoes are characterized by their dome-like shape, resembling a warrior's shield laid flat on the ground. The gentle slopes result from the low angle of the lava flows, which contrasts with more explosive volcano types.

5 Must Know Facts For Your Next Test

1. Shield volcanoes typically have a broad, shield-like profile due to the low viscosity of their lava flows, which allows the lava to travel far from the eruption site.
2. These volcanoes are often associated with hotspot activity, where magma rises from deep within the Earth, creating islands like those found in the Hawaiian chain.
3. The eruptions of shield volcanoes are generally non-explosive and produce relatively gentle lava flows rather than violent explosions.
4. Some famous examples of shield volcanoes include Mauna Loa and Kilauea in Hawaii, both of which are among the most active volcanoes on Earth.
5. Due to their shape and eruption style, shield volcanoes can cover large areas and significantly alter landscapes over time, contributing to various geological formations.

Review Questions

• Compare shield volcanoes to other types of volcanoes in terms of eruption style and shape.
  • Shield volcanoes differ from stratovolcanoes and cinder cone volcanoes mainly in their eruption style and shape. Shield volcanoes have low-viscosity lava that leads to non-explosive eruptions, resulting in their broad, gently sloping profiles. In contrast, stratovolcanoes have steeper profiles due to more viscous lava that can trap gases, leading to explosive eruptions. Cinder cone volcanoes are generally smaller and formed from ash and tephra ejected during eruptions, resulting in steep sides.
• Discuss how shield volcanoes contribute to the formation of new landforms and ecosystems.
  • Shield volcanoes play a significant role in landform creation as their extensive lava flows can cover vast areas, building up new terrain over time. As these landforms emerge, they create unique ecosystems that can adapt to the volcanic soil rich in minerals. The initial barren landscape gradually transforms as plants colonize the area, promoting biodiversity. This process showcases how geological activity not only shapes the Earth's surface but also influences biological diversity.
• Evaluate the impact of shield volcanoes on human settlements and local economies.
  • Shield volcanoes can have both positive and negative impacts on human settlements and local economies. On one hand, they provide fertile soils that support agriculture due to mineral-rich ash deposits, benefiting farming communities. On the other hand, their eruptions can threaten nearby towns with lava flows and potential gas emissions. Understanding these dynamics is crucial for effective risk management and planning for communities living near active shield volcanoes, ensuring they balance agricultural benefits with safety measures.

Related terms

Basalt: A dark, fine-grained volcanic rock that is the primary type of lava emitted by shield volcanoes, known for its low viscosity.

Hot Spot: An area in the mantle from which heat rises as a thermal plume, leading to volcanic activity, often creating shield volcanoes like those in Hawaii.

Lava Flow: The movement of molten rock (lava) that erupts from a volcano and flows across the surface, crucial in shaping the profile of shield volcanoes.