Which hazards are commonly associated with stratovolcanoes?

• A. Tephra
• B. Lahars
• C. Pyroclastic flows
• D. All of the above

Answer: (D)

Stratovolcanoes erupt explosively because their magma is viscous and traps gases. When they blow, they eject tephra such as ash clouds, pumice, and volcanic bombs. This tephra can blanket regions, cause roof collapses, and disrupt aviation, illustrating how explosive eruptions project material into the atmosphere and surrounding landscape.

Explosive activity also drives pyroclastic flows—hot gases mixed with volcanic ash and pumice that race down the volcano’s slopes. These flows move incredibly fast and are devastating to anything in their path, highlighting the violent, ground-hugging aspect of stratovolcano eruptions.

Lahars, or volcanic mudflows, form when tephra-rich water—from melting snow and ice or heavy rainfall—produces a slurry that flows down river valleys. They can travel great distances, burying settlements and reshaping valleys long after the eruption itself.

All of these hazards arise from the way stratovolcanoes build up layered deposits and erupt explosively, so they are commonly associated with these volcanoes.