Question

Match each of these volcanic regions with one of the three zones of volcanism (convergent plate boundaries, divergent plate boundaries, or intraplate volcanism): a. Crater Lake e. Yellowstone b. Hawaii's Kilauea f. Mount Pelée c. Mount St. Helens g. Deccan Plateau d. East African Rift h. Mount Fujiyama

Short answer

Crater Lake, Mount Pelée, St. Helens, and Fujiyama: convergent; East African Rift: divergent; Hawaii's Kilauea, Yellowstone, and Deccan Plateau: intraplate.

Step-by-step solution

Understand Volcanism Zones

Volcanism occurs in three primary zones: convergent plate boundaries, divergent plate boundaries, and intraplate volcanism. Convergent plate boundaries occur where tectonic plates collide, leading to the formation of volcanoes. Divergent boundaries occur where plates move apart, allowing magma to rise. Intraplate volcanism occurs within a tectonic plate, away from the borders.

Identify Volcanic Regions at Convergent Boundaries

These regions are typically characterized by subduction zones where one plate moves under another. Notable volcanoes in this category include Crater Lake, Mount Pelée, Mount St. Helens, and Mount Fujiyama. All these are products of convergent plate boundary activity.

Identify Volcanic Regions at Divergent Boundaries

Divergent boundaries are characterized by mid-ocean ridges and rift valleys where plates pull apart and magma rises to fill the gap. The East African Rift is a prime example, as it is a continental rift zone where divergent boundary volcanism occurs.

Identify Intraplate Volcanic Regions

Intraplate volcanism often creates hotspots or large volcanic plateaus away from plate boundaries. Hawaii's Kilauea and Yellowstone are results of intraplate volcanic activity. The Deccan Plateau is another example, formed by a massive volcanic eruption within the Indian Plate.

Key concepts

Convergent Plate Boundaries

Convergent plate boundaries are fascinating zones where two tectonic plates collide. When these plates meet, one plate is often forced below the other in a process known as subduction. This process leads to intense pressure and heat, melting the subducted plate and creating magma. This magma is lighter than the surrounding rock, so it rises through the overlying crust, forming volcanoes.

Volcanoes at convergent boundaries are typically explosive and can be found on land as well as in ocean trenches, which are deep valleys in the ocean floor. Some well-known volcanoes that form due to these boundaries include Crater Lake in Oregon, a caldera formed by the collapse of a volcanic eruption, Mount Pelée in the Caribbean, and Japan’s iconic Mount Fujiyama. Both Mount St. Helens in Washington and Mount Pelée are excellent examples of how volcanic activity at convergent boundaries can have dramatic and explosive impacts.

Divergent Plate Boundaries

Divergent plate boundaries occur when two tectonic plates move apart from each other. This boundary is most commonly seen at mid-ocean ridges, where it results in new seafloor being created. As the plates separate, magma from the mantle rises to fill the void, then cools to form new crust.

These areas can also occur on continents. The East African Rift, for instance, is a continental rift that showcases how divergent boundaries create volcanic activity on land. As the continental crust stretches and thins, it can lead to the development of rift valleys and volcanic activity.

• Volcanism here is generally less explosive compared to convergent boundaries.
• The movement of the plates at these boundaries is usually more gradual and less noticeable.

These volcanic regions are marked by the steady outpouring of basaltic lava, which can create extensive lava fields.

Intraplate Volcanism

Intraplate volcanism offers a unique perspective on volcanic activity, as it occurs within tectonic plates rather than at their boundaries. The primary driving force behind intraplate volcanism is a thermal anomaly or hotspot. These hot regions in the mantle can cause rock to melt and create magma, which then rises to form volcanoes.

Hawaii's Kilauea is an example of an intraplate hotspot. Despite being located far from any plate boundary, it remains one of the most active volcanoes on Earth. Similarly, Yellowstone sits atop a large hotspot beneath the North American Plate. This hotspot activity has led to the formation of one of the world's largest active volcanic systems, characterized by its geothermal features such as geysers and hot springs.

• Intraplate volcanoes are generally less explosive but can produce significant lava flows.
• The Deccan Plateau in India, formed by massive volcanic eruptions, showcases the potential scale of intraplate volcanic events.

Understanding these systems provides insight into how Earth's mantle dynamics can influence surface geology, even away from plate edges.