Volcano

If a volcano’s magma is high in silica, the volcano will probably

• erupt quietly.

• remain dormant.

• erupt explosively.

• produce dark-colored lava

When groundwater heated by magma rises to the surface and collects in a natural pool, it is called a

• hotspring

• geyser

• vent

• pyroclastic flow

In volcanic areas, groundwater heated by magma is a source of

• lava flows

• silica

• geothermal energy.

• pyroclastic flows.

The major ingredient of magma is

• silica

• dissoleved gases

• obsidian

• ash

What triggers the small earthquakes that occur around a volcano before an eruption?

• upward movement of magma

• pyroclastic flow

• cooling magma inside the crust

• plate movements

Before lava reaches the surface, the molten material is called

• rock

• magma

• volcanic ash

• liquid fire

The huge hole left by the collapse of a volcanic mountain is called a

• dome

• caldera

• cinder cone

• shield volcano

If geologists detect many small earthquakes in the area near a volcano, what can they infer about the volcano?

• It is dormant.

• It is probably about to erupt.

• It is extinct

• It is a good source of geothermal energy.

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

• high silica content

• high viscosity

• low viscosity

• medium viscosity

What provides the force that causes magma to erupt to the surface?

• the silica in the magma

• dissolved gases trapped in the magma

• gravity in the lithosphere

• the density of the magma