Question

What are the two primary modes in which volcanoes typically erupt?

• A. Underwater and surface eruptions
• B. Ash and gas eruptions
• C. Explosive and Effusive eruptions
• D. D) Slow and rapid eruptions

Answer 1

Answer:

C. Explosive and Effusive eruptions

Volcanoes typically erupt in two primary modes:

• Explosive Eruptions:

  • Characteristics: These are violent and forceful eruptions.

  • Magma Type: Usually associated with highly viscous (thick and sticky) magma that traps gases.

  • Output: They violently blast ash, gas, and rock fragments high into the atmosphere, often forming towering eruption columns and pyroclastic flows.

  • Example: Mount St. Helens (1980), Mount Vesuvius (79 AD).

• Effusive Eruptions:

  • Characteristics: These are relatively gentle and non-explosive eruptions.

  • Magma Type: Involve low-viscosity (runny) magma that allows gases to escape easily.

  • Output: They produce steady flows of molten rock (lava) that flow out of the volcano onto the surface.

  • Example: Kilauea in Hawaii.