Volcanoes and Their Hazards

What is the primary cause of magma reaching the Earth's surface to form volcanoes?

• Erosion of the Earth's crust

• Condensation of atmospheric gases

• Evaporation of ocean water

• Movement of tectonic plates

Which underground structure is formed when magma cuts through rock layers?

• Sill

• Dyke

• Laccolith

• Vent

What is a common sign that a volcano might erupt soon?

• Decrease in local wildlife

• Increase in earthquake activity

• Sudden drop in temperature

• Formation of new rivers

What type of lava flow is characterized by being highly fluid?

• Aa flow

• Scoria flow

• Pahoehoe flow

• Pyroclastic flow

What is the primary danger of pyroclastic flows?

• They travel at high speeds

• They create large craters

• They emit toxic gases

• They cause landslides

What is the size range of lapilli debris?

• Less than 2 millimeters

• 2 to 64 millimeters

• Exactly 64 millimeters

• More than 64 millimeters

What is a lahar?

• A volcanic gas

• A type of volcanic rock

• A mixture of mud and water

• A type of lava flow

What caused the Tangiwai disaster in New Zealand?

• A tsunami

• A lahar from Mount Ruapehu

• A volcanic eruption

• An earthquake

What can trigger a volcanic landslide besides an eruption?

• High winds

• Volcanic ash

• Heavy rainfall

• Drought conditions

What natural phenomenon can be generated by ash clouds from volcanic eruptions?

• Tornadoes

• Hurricanes

• Lightning discharges

• Earthquakes