How to Classify Volcanoes

Summary

This lesson explores the different types of volcanoes, including shield, composite, cinder cones, and lava domes. It highlights how their shapes, eruption styles, and magma types vary, influencing the intensity of eruptions. The session uses visuals and interactive activities to distinguish these volcanoes, such as the gentle slopes of shield volcanoes formed by fluid lava flows, versus the steep, more explosive composite volcanoes. Smaller volcano types like cinder cones and lava domes are also examined. Students learn to classify volcanoes and assess volcanic hazards, enhancing their understanding of Earth's geological processes.

Takeaways

• 🌋 Volcanoes vary in appearance based on their location and type, affecting the potential risk they pose.
• 🌋 There are two primary types of large volcanoes: shield volcanoes and composite volcanoes.
• 🌋 Shield volcanoes have low-angle, broad profiles, resembling an overturned warrior's shield.
• 🌋 Lava from shield volcanoes is fluid, allowing it to flow long distances through lava tubes or channels.
• 🌋 Mauna Loa in Hawai'i is the largest shield volcano, spanning over 100 km and rising over 9 km from the sea floor.
• 🌋 Composite volcanoes have steeper profiles and are characterized by violent eruptions with viscous lava and tephra.
• 🌋 Composite volcanoes form at subduction zones, while shield volcanoes often form at hot spots and rift systems.
• 🌋 Smaller volcanoes like cinder cones and lava domes are significantly smaller, with heights measured in hundreds of meters.
• 🌋 Cinder cones are formed by single eruptions, with fragments of cooled lava known as scoria.
• 🌋 Lava domes form from slow-moving, highly viscous lava, often within composite volcanoes, and can create hazards like pyroclastic flows.

Q & A

What are the two main types of volcanoes discussed in the lesson?

The two main types of volcanoes discussed are shield volcanoes and composite volcanoes.

How does the shape of a shield volcano differ from a composite volcano?

Shield volcanoes have a low-angle, broad triangular profile, resembling an overturned warrior’s shield, while composite volcanoes have a steeper, more triangular profile.

What type of volcanic activity is typically associated with shield volcanoes?

Shield volcanoes are typically associated with the eruption of thin, fluid lava flows that can travel long distances before cooling and solidifying.

Why are eruptions of composite volcanoes considered more violent than those of shield volcanoes?

Eruptions of composite volcanoes are more violent because their magma is more silica-rich, making the lava thicker and more viscous, leading to explosive eruptions with tephra and other volcanic debris.

What is a key difference in scale between larger volcanoes (shield and composite) and smaller ones (cinder cones and lava domes)?

Larger volcanoes like shield and composite volcanoes are measured in tens of kilometers in width and thousands of meters in height, while smaller volcanoes like cinder cones and lava domes are measured in hundreds of meters in height.

What volcanic hazards are associated with lava domes?

Lava domes can create hazardous pyroclastic flows when their steep slopes collapse.

Where are shield volcanoes commonly found, and what geological features do they typically form along?

Shield volcanoes are commonly found at hot spots and along oceanic and continental rift systems.

What are cinder cones typically composed of, and how are they formed?

Cinder cones are composed of tephra, which consists of lava fragments that cool and solidify as they fall to the ground after being blasted into the air.

What is scoria, and where is it typically found?

Scoria is cooled lava fragments that often contain air bubbles. It is typically found in cinder cones.

What is a notable feature of Mauna Loa, a famous shield volcano in Hawai'i?

Mauna Loa is more than 100 km across and rises over 9 km from the sea floor, making it taller than Mount Everest.