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Volcanic Activity and Natural Disasters

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Questions and Answers

Briefly describe the primary cause of volcanic eruptions, linking it to underground pressure.

Volcanic eruptions are primarily caused by the buildup of pressure from magma (molten rock and gas) beneath the Earth's surface.

Explain how a volcanic eruption could trigger a tsunami, detailing the mechanism involved.

A volcanic eruption can trigger a tsunami if it occurs near or under the ocean. The sudden displacement of water caused by the eruption or associated landslides generates a tsunami.

Describe a scenario where a volcanic eruption could indirectly lead to widespread flooding, not directly caused by lava flow.

A volcanic eruption can melt glaciers or ice caps, causing a large influx of meltwater that leads to downstream flooding in surrounding areas.

Outline the relationship between volcanic eruptions and earthquakes, including why one might cause the other.

Volcanic eruptions and earthquakes are related because the movement of magma beneath the surface can cause stress on surrounding rocks, leading to earthquakes. Conversely, large earthquakes can sometimes trigger volcanic activity by altering pressure within the Earth. Signup and view all the answers

Describe how the release of gases during a volcanic eruption contributes to its explosive nature.

As magma rises, pressure decreases, allowing dissolved gases to expand rapidly. This expansion can cause a violent explosion if the gases are trapped within viscous magma. Signup and view all the answers

Differentiate between effusive and explosive volcanic eruptions, focusing on the properties of the magma involved.

Effusive eruptions involve low-viscosity magma with lower gas content, resulting in lava flows. Explosive eruptions involve high-viscosity magma with high gas content, leading to violent explosions. Signup and view all the answers

Explain how the composition of magma, specifically its silica content, affects the viscosity and eruption style of a volcano.

Magma with higher silica content is more viscous, which traps gases and leads to more explosive eruptions. Lower silica content results in less viscous magma and effusive eruptions. Signup and view all the answers

Describe how monitoring gas emissions from a volcano can help in predicting potential eruptions.

Changes in the type and amount of gases emitted from a volcano can indicate changes in magma activity and pressure. An increase in sulfur dioxide emissions, for example, might signal an impending eruption. Signup and view all the answers

Explain why some volcanic eruptions are more likely to cause tsunamis than others, relating it to the location and type of eruption.

Volcanic eruptions that occur near or beneath the ocean surface or involve the collapse of volcanic islands are more likely to generate tsunamis due to the direct displacement of large volumes of water. Signup and view all the answers

Describe how lahars are formed during or after a volcanic eruption and explain why they are dangerous.

Lahars are formed when volcanic ash and debris mix with water from rainfall, melted snow, or nearby rivers, creating a mudflow. They are dangerous due to their speed, density, and ability to travel long distances, burying or destroying everything in their path. Signup and view all the answers

Flashcards

Volcanic Eruption

A natural disaster caused by the buildup of pressure from underground magma, a mixture of molten rock and gas.

Study Notes

Magma, a mix of molten rock and gas, causes underground pressure buildup.
This pressure increase can lead to significant natural catastrophes.
Volcanic activity can trigger tsunamis, causing widespread coastal flooding.
Floods can result from volcanic eruptions melting glaciers and ice caps.
Earthquakes are frequently associated with volcanic activity.

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