Volcanic Activity and Magma Composition Quiz

Which is NOT a common gas in magma?

• A. methane gas

• B. carbon dioxide

• C. sulfur dioxide

• D. water vapor

Which type of lava will offer the least resistance to flow?

• A. Andesitic

• B. Basaltic

• C. Rhyolitic

• D. Basaltic and Rhyolitic

If a volcano's magma is high in silica, how will you describe to its volcanic activity?

• A. It will erupt quietly

• B. It will remain dormant

• C. It will erupt explosively

• D. It will produce dark-colored lava

Viscosity is a measure of a material's resistance to flow. Which DOES NOT affect the viscosity of magma?

• A. location of magma

• B. temperature of the magma

• C. chemical composition of the magma

• D. presence of dissolved gases in the magma

Which is TRUE about the composition of magma?

• A. It contains ash, dust, and lava

• B. It contains dissolved gases only.

• C. It contains fragmented rocks only.

• D. It contains both dissolved gases and fragmented materials.

Which are needed in the formation of magma?

• A. composition, pressure, temperature

• B. composition, pressure, density

• C. pressure, temperature, distance from the surface

• D. pressure, temperature, volume

Several kilometers from a volcano, a geologist observes an old lava flow made up of dark- colored basalt rock. The geologist infers that the lava must have had____________.

• A. low viscosity

• B. high viscosity

• C. medium viscosity

• D. high silica content

The magma in the chamber of a volcano has a very high amount of silica. If the volcano would erupt, which might happen?

• A. The lava would flow very slowly

• B. The volcano would erupt violently

• C. The volcano would erupt non-explosively

• D. There would be a build-up of pressure below the crater