Which type of volcano is large, steep-sided, and known for violent eruptions?

• A. Composite Volcano
• B. Cinder Cone Volcano
• C. Caldera
• D. Earthquake

Answer: (A)

Magma viscosity and how eruptions build a volcano determine its shape and eruptive style. Composite volcanoes, also called stratovolcanoes, grow from alternating layers of viscous lava flows and erupted ash and pumice. That sticky magma, higher in silica, traps gases until they explode violently, producing ash plumes, pumice fell, and pyroclastic flows. Over time, these layered deposits create a large, steep-sided cone that can erupt with major violence, exactly fitting the description of being both big and violently active.

Cinder cones are built from loose tephra ejected near the vent, forming smaller, cone-shaped mounds rather than tall, layered structures. A caldera is a huge crater formed when a magma chamber collapses after a massive eruption, not a typical steep-sided volcano. An earthquake is not a volcano at all.