Volcanoes and Eruptions Quiz

Volcanoes and Eruptions

• Mount Lassen was the last volcano to erupt before Mount St. Helens, which erupted in 1980 and caused 59 fatalities.
• Mount St. Helens erupted a cubic kilometer of ash and rock debris, including pyroclastic and mud flows, and caused significant devastation to the area.
• Kilauea, on the other hand, is a basaltic volcano that continuously erupts every couple of years, while Mount St. Helens was an intermediate and acidic volcano.
• The composition of magma/lava, temperature, and gas content are three key factors that determine the nature of a volcanic eruption.
• Mafic rocks are rich in silicates and high in iron and magnesium, while felsic rocks are granitic in composition and crystallize slowly.
• Basaltic magmas come from partial melting of the upper mantle, while granitic magmas come from partial melting of the continental crust.
• Mount St. Helens is on a convergent plate boundary, while Kilauea is on a hot spot.
• The eruption of Mount St. Helens was a lateral eruption, which means it erupted sideways, releasing pressure from the magma chamber and causing a massive explosion.
• The volcanic mudflows, called lahars, are a mixture of water and ash high in silica and behave differently than regular mud, causing significant damage.
• Iceland is currently experiencing a swarm of earthquakes that could signal an upcoming volcanic eruption.
• Scientists can predict volcanic eruptions based on changes in gas composition and temperature of the ground.
• A famous video shows a man filming the eruption of Mount St. Helens, which took longer than expected to erupt, causing significant devastation to the area.

Volcanic Hazards: Pyroclastic Flows, Lahar, and Climate Effects

• Composite volcanoes are made up of both pyroclastic eruptions and lava flows.
• The composition of a composite volcano can change over time due to varying magmatic compositions.
• Most composite volcanoes are located adjacent to the Pacific Ocean due to subduction zones.
• The three types of volcanoes are cinder cones, stratovolcanoes, and shield volcanoes.
• Pyroclastic flows are composed of ash, dust, and cinders that move down the sides of mountains at high speeds and temperatures.
• Pyroclastic flows are more deadly than lava and can cause asphyxiation and encase victims in ash.
• Lahars are volcanic mudflows that can occur when snow or ice is present on the mountain.
• Lahars can be devastating and cover entire towns.
• Volcanic ash can block out the sun and cause a cooling effect on the climate.
• One notable effect on climate was a mass extinction event 250 million years ago due to volcanic eruptions.
• The eruption caused gases and ash to cover the planet, killing 90% of the species at the time and leading to the rise of dinosaurs and eventually humans.
• Volcanic ash can also cause respiratory problems and affect aviation.