Which volcano type is typically characterized by steep sides and explosive eruptions due to high-viscosity magma?

Which volcano type is typically characterized by steep sides and explosive eruptions due to high-viscosity magma?

• A. Stratovolcanoes
• B. Shield volcanoes
• C. Volcanic cones
• D. Calderas

Answer: (A)

High-viscosity magma traps gases and builds up pressure, so eruptions tend to be violent and eject ash, pumice, and other pyroclastic material rather than lava flows that travel far. That explosive behavior, combined with layered deposits from repeated eruptive cycles, creates tall, steep-sided cones. This is exactly what stratovolcanoes are known for: they grow from alternating lava flows and tephra, fed by magma with relatively high silica content (andesitic to rhyolitic). Shield volcanoes, by contrast, form from low-viscosity magma that flows easily, resulting in broad, gently sloping profiles and mostly effusive eruptions. Calderas are large depressions created by the collapse of a magma chamber after major eruptions, not the steep-sided, explosive-build-up style described here. The term volcanic cones is too general to pinpoint this specific behavior.

High-viscosity magma traps gases and builds up pressure, so eruptions tend to be violent and eject ash, pumice, and other pyroclastic material rather than lava flows that travel far. That explosive behavior, combined with layered deposits from repeated eruptive cycles, creates tall, steep-sided cones. This is exactly what stratovolcanoes are known for: they grow from alternating lava flows and tephra, fed by magma with relatively high silica content (andesitic to rhyolitic).

Shield volcanoes, by contrast, form from low-viscosity magma that flows easily, resulting in broad, gently sloping profiles and mostly effusive eruptions. Calderas are large depressions created by the collapse of a magma chamber after major eruptions, not the steep-sided, explosive-build-up style described here. The term volcanic cones is too general to pinpoint this specific behavior.