Question

Which of the following statements about different types of volcanic eruptions are correct?

1. Explosive eruptions are characterized by the violent expulsion of ash, gas, and rock fragments.
2. Effusive eruptions involve a relatively gentle outflow of lava.
3. The 'glowing avalanche' is a type of effusive eruption, known for its slow movement.

• A. i
• B. i, ii
• C. ii മാത്രം
• D. i മാത്രം

Answer 1

Answer:

B. i, ii

Volcanic eruptions are broadly classified into two primary modes based on their explosivity. Explosive eruptions occur when highly viscous magma traps gases, leading to immense pressure buildup. When this pressure is released, it results in a violent explosion, ejecting ash, pumice, and gas high into the atmosphere, often forming towering eruption columns. Mount St. Helens in 1980 is a classic example. In contrast, effusive eruptions are characterized by less viscous, free-flowing lava that gently spills out of the vent, forming lava flows. These eruptions are generally less destructive than explosive ones. Kilauea in Hawaii frequently exhibits effusive eruptions.