Volcanoes are openings through which material from inside a planet reaches its surface. Their locations are closely connected to the movement of tectonic plates, so learning where and how they form helps explain patterns of volcanic activity around Earth.
A volcano is a vent or fissure in a planetary crust through which lava, volcanic ash, and gases can escape. These materials are supplied by magma beneath the surface. Magma is molten rock underground; once it reaches the surface, it is called lava.
All flashcards
What is a volcano?
A vent or fissure in a planetary crust that allows lava, volcanic ash, and gases to escape.
What is a divergent boundary?
A boundary where tectonic plates move apart. Rising mantle rock can partially melt as pressure decreases, producing magma and new crust.
What is subduction?
The process in which one tectonic plate, commonly an oceanic plate, sinks beneath another. Water released from the sinking plate can help generate magma.
What is a volcanic arc?
A chain of volcanoes that forms above a subduction zone.
How can a hotspot form an island chain?
A moving plate passes over a relatively fixed magma source; older volcanoes move away and become inactive as new ones form above the hotspot.
Quiz questions
What is a volcano?Answer: A vent or fissure in a planetary crust through which lava, ash, and gases can escape.
What happens at a divergent plate boundary that can produce magma?Answer: Plates move apart, allowing mantle to rise and melt as pressure falls.
Why are many volcanic arcs found near subduction zones?Answer: Water released by the sinking plate helps generate magma in the mantle above it.
A chain of islands has volcanoes that become older farther from one end. Which setting best explains this pattern?Answer: A tectonic plate moving across a relatively fixed hotspot.
Which plate-boundary setting is generally least associated with volcano formation?Answer: A transform boundary where plates slide past one another.
Based on the Wikipedia article Volcano, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.