Volcanic Eruption

Which of the following describes a strombolian eruption?

• a periodic weak to violent eruption characterized by fountain lava

• excessively explosive type of eruption of gas and pyroclastics

• characterized by tall eruption columns that reach up to 20 km high with pyroclastic flow and ashfall

• all of the above

Which is NOT a factor affecting volcanoes’ eruptive style?

• age of magma

• temperature of magma

• amount of dissolved gases

• chemical composition of magma

Which statement is correct?

• the higher the temperature of magma is, the lower is its viscosity

• magma with high silica content are less viscous than with low silica content

• magma with more silica content is relatively fluid and travels far before solidifying

• all of the above

Which describes a volcano with quiet eruption?

• magma has high viscosity

• magma has low silica content

• magma has high silica content

• magma doesn’t always flow out of the vent

What type of eruption is characterized by excessively explosive type of eruption of gas and pyroclastics?

• Vulcanian

• strombolian

• Plinian

• Phreatomagmatic

What are solid rock fragments that are ejected during eruption?

• magma

• silica

• lahar

• pyroclastic material

Which of the following statements listed below is NOT a positive aspect of volcanic eruption?

• The dramatic scenery of volcanic eruption attacts tourists.

• lava flows and lahars clear areas of woodland, agriculture and destroy settlements

• The lava and ash deposited during a volcanic eruption breaks down to provide valuable nutrients for the soil

• all of the above

Which of the following is NOT a short term response to an eruption?

• aid from abroad

• building a volcanic observatory

• evacuating people who may be affected by the eruption

• all of the above

All of the following events could indicate an impending eruption EXCEPT:

• a highly eroded, volcanic peak.

• swarms of small earthquakes in the region

• a measurable bulge or swelling of the volcano

• discovery of new hot springs around the volcano

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

• the silica in the magma

• gravity in the lithosphere

• the density of the magma

• dissolved gases trapped in the magma