Question

What characterizes an explosive volcanic eruption?

• A. Relatively gentle outflow of lava
• B. Calm release of steam and water
• C. Violent expulsion of ash, gas, and rock fragments
• D. Slow emission of only gases

Answer 1

Answer:

C. Violent expulsion of ash, gas, and rock fragments

An explosive volcanic eruption is primarily characterized by the violent expulsion of ash, gas, and rock fragments.

• Violent Force: Unlike gentle lava flows, explosive eruptions are driven by immense pressure build-up within the volcano.

• High Gas Content & Viscosity: They typically involve magma that is rich in trapped gases and is highly viscous (thick and sticky). This prevents gases from escaping easily.

• Fragmentation: As the gas pressure builds and then suddenly releases, the magma is shattered into tiny fragments (ash) and larger pieces (rock fragments or bombs).

• Eruption Column: This material is propelled high into the atmosphere, forming towering eruption columns.

• Pyroclastic Flows: The collapse of these columns can generate extremely dangerous, fast-moving, superheated pyroclastic flows.