Chapter 4 - Volcanoes and Volcanic Processes Flashcards
What determines the viscosity of magma?
Its temperature, silica content, and gas content.
What is the difference between Pahoehoe and Aa lava?
Pahoehoe has a smooth, ropy texture, while Aa is rough and jagged.
What is a pyroclastic flow?
A fast-moving, deadly flow of hot gas, ash, and volcanic materials down the side of a volcano.
What are the three main types of volcanic material?
Lava flows, gases, and pyroclastic debris.
What is a lahar?
A volcanic mudflow typically triggered by melting snow or heavy rain on volcanic debris.
How do volatiles in magma influence the style of a volcanic eruption?
Volatiles lower the melting point of rock and increase pressure in the magma. When released, they can cause explosive eruptions (e.g., in felsic magmas) or gentler, effusive eruptions (e.g., in mafic magmas).
Compare the eruptive behavior of shield volcanoes and stratovolcanoes.
Shield volcanoes (e.g., in Hawaii) have gentle slopes and eruptions with low-viscosity lava, whereas stratovolcanoes have steep sides and more explosive eruptions due to higher-viscosity magma.
