GEOL105- Chapter 5 Part A

Magma with a higher silica content will also have a higher viscosity. A.True B.False

True

Which of the following lists magma types in order of increasing viscosity (LEAST viscous first)? A.Basaltic, andesitic, rhyolitic B.Basaltic, rhyolitic, andesitic C.Rhyolitic, basaltic, andesitic D.Rhyolitic, andesitic, basaltic E.Andesitic, rhyolitic, basaltic

A.Basaltic, andesitic, rhyolitic

Which volcano type is composed mostly of lava flows? A.Shield volcano B.Stratovolcano C.Lava dome D.Cinder cone E.Composite cone

A.Shield volcano

Which volcano type involves layers of pyroclastic debris and lava flows? A.Stratovolcano B.Lava dome C.Cinder cone D.Shield volcano

A.Stratovolcano

Shield volcanoes are the most dangerous volcanoes because they are so big. A. True B. False

B. False

Which of the following environments has the most explosive volcanoes? A.Hotspots in the ocean B.Hotspots on land C.Continental rift zones D.Mid-ocean ridges E.Subduction zones

B.Hotspots on land

At which plate boundary is more viscous lava found? A.Oceanic hotspots B.Oceanic subduction zones C.Oceanic divergent plate boundaries D.Continental rift zones E.Shield volcanoes on the ocean floor

B.Oceanic subduction zones

Where is the majority of lava extruded? A.At subduction zones B.At hotspots C.At divergent plate boundaries D.At transform plate boundaries E.At convergent plate boundaries

C.At divergent plate boundaries

Which of the following is FALSE about caldera eruptions? A.Caldera eruptions erupt enough ash to potentially alter global climate. B.Caldera eruptions are very rare. C.Caldera eruptions result in towering volcanic mountains. D.Caldera eruptions are extremely violent in nature. E.Caldera eruptions have occurred in the United States in geologic history.

C.Caldera eruptions result in towering volcanic mountains.

Which type of magma typically results in the greatest explosive events? A.Basaltic B.Andesitic C.Rhyolitic D.Pahoehoe E.Aa

C.Rhyolitic

Which of the following is FALSE about magma? A.Most magmas come from melting of the asthenosphere. B.Some magma comes from rocks melted through decompression. C.Tectonic plates move around on an underground ocean of magma. D.Adding volatiles, such as water, to rock decreases its melting point and makes it easier to melt.

C.Tectonic plates move around on an underground ocean of magma.

What are volatiles? A.Large blocky projectiles fired from a volcano B.Small abrasive particles such as volcanic ash that can make it difficult to breath C.Thin fibers of lava that is extruded from a volcano D.Silica tetrahedra in magma E.Gases trapped in the magma

E.Gases trapped in the magma

Which of the following is NOT a reason why stratovolcanoes are dangerous? A.They are associated with higher viscosity magma. B.They have dormant periods between eruptions, which can make people underestimate their hazard. C.They erupt abundant pyroclastic debris. D.They involve explosive eruptions. E.They erupt fast-moving lava flows that kill many people.

E.They erupt fast-moving lava flows that kill many people.