Shield Volcano

Definition

A shield volcano is a broad, gently sloping landform created by the eruption of low-viscosity basaltic lava that can flow over great distances. This type of volcano is characterized by its shield-like shape, formed from numerous layers of lava flows that spread out in all directions. The eruption style is typically non-explosive, resulting in the gradual build-up of the volcano and a wide base.

5 Must Know Facts For Your Next Test

1. Shield volcanoes are primarily built from fluid lava flows that can travel long distances before solidifying, contributing to their broad, gentle slopes.
2. The Hawaiian Islands are a classic example of shield volcanoes, with Mauna Loa being one of the largest active shield volcanoes in the world.
3. Unlike stratovolcanoes, which are steep and have explosive eruptions, shield volcanoes typically produce non-explosive eruptions due to their low-viscosity lava.
4. Eruptions from shield volcanoes can last for extended periods, sometimes for decades or centuries, resulting in significant landform changes over time.
5. The gentle slopes of shield volcanoes allow for ecosystems to develop at various elevations, supporting diverse plant and animal life.

Review Questions

• How does the eruption style of shield volcanoes compare to that of stratovolcanoes, and what are the implications for their shapes?
  • Shield volcanoes erupt mainly low-viscosity basaltic lava that flows smoothly and evenly across large areas, leading to their broad, gentle slopes. In contrast, stratovolcanoes erupt more viscous lava that tends to pile up near the vent, resulting in steep, conical shapes. The differences in eruption styles greatly influence the morphology of these volcanoes: shield volcanoes appear flattened and broad while stratovolcanoes are tall and steep.
• Discuss the geological processes that lead to the formation of shield volcanoes and their role within hotspot regions.
  • Shield volcanoes are formed when magma from a hotspot rises through the Earth's crust and erupts on the surface as basalt lava. The repeated flows from these eruptions layer over time, creating a gently sloping structure. Hotspot regions provide a continuous source of magma beneath stationary tectonic plates, allowing shield volcanoes to form and evolve over time as lava flows build up around the vent.
• Evaluate the environmental impacts of long-term eruptions from shield volcanoes on surrounding ecosystems.
  • Long-term eruptions from shield volcanoes can significantly alter local ecosystems by changing landforms and creating new habitats. As lava flows cool and solidify, they create new substrates for plant colonization. Over time, these areas can develop into rich ecosystems; however, initial volcanic activity may also destroy existing habitats. Additionally, volcanic gases released during eruptions can affect air quality and climate conditions in nearby regions.

Related terms

Basalt: A dark, fine-grained volcanic rock that is rich in iron and magnesium, typically forming the primary lava flow of shield volcanoes.

Volcanic Activity: The processes and phenomena associated with the movement of magma, gases, and volcanic materials from the Earth's interior to the surface.

Hotspot: An area in the mantle where heat causes melting of the crust, often resulting in volcanic activity and the formation of shield volcanoes, such as those in Hawaii.