How does magma commonly form inside Earth?

Which description correctly identifies the contents of magma?

Which element makes up the greatest proportion by mass of typical silicate magma?

What does viscosity measure?

A molten sample is warmed without changing its composition or crystal content. Compared with its earlier state, how should it behave?

At the same temperature and crystal content, how does a higher silica proportion generally affect molten rock?

Which change generally increases magma's viscosity, assuming its other properties remain unchanged?

Why can thick magma contribute to pressure buildup before an explosive eruption?

Basaltic magma usually moves easily and allows gas to escape. Which eruption behavior is most likely?

At equal temperature and crystal content, which magma in the table is most likely to trap gas and produce an explosive eruption?

What is the formation of gas bubbles in rising molten material called?

Why can some volcanoes develop broad bases and gentle slopes?

What builds the layered structure typical of a composite volcano?

Small, steep volcanic hills made mainly of loose fragments around an opening are usually classified as what?

Which substance is commonly the most abundant gas released by volcanic magma?

A Philippine volcano has a documented eruption within the last 600 years. How is it classified by activity?

Groundwater touches hot rock and blasts out steam and older fragments without fresh molten material. What eruption type is this?

A fast, ground-hugging cloud of hot gas, ash, and rock rushes down a volcano. Which hazard is this?

Heavy rain mixes with loose volcanic debris and sends a muddy mixture down a valley. What is this hazard called?

After ashfall in Albay, residents inhale fine volcanic particles. Which body system is most directly affected?