Understanding Volcanoes: Geological Features and Tectonic Plates

What type of volcanoes are responsible for most of the volcanic activity on Earth?

Composite volcanoes
Volcanoes at divergent plate boundaries (correct)
Shield volcanoes
Cinder-cone volcanoes

What is the difference between magma and lava?

Magma is denser than lava
Magma contains more gas than lava
Lava is only found at subduction plate boundaries
Magma is molten rock beneath the surface, while lava is molten rock that erupts onto the surface (correct)

What do composite volcanoes possess that cinder-cone volcanoes do not?

Presence of calderas and multiple vents (correct)
Gentle slope
Explosive eruptions
Conical structure

What causes the formation of volcanoes according to the text?

Intense heat and pressure generated by tectonic plate movement (C) Signup and view all the answers

What types of materials can volcanoes eject according to the text?

Steam, clouds of molten ash, and super-heated rock fragments (C) Signup and view all the answers

What is the main difference between lava flows and pyroclastic flows?

Lava flows are slower and mainly consist of molten rock, while pyroclastic flows are faster and mainly consist of solid particles. (B) Signup and view all the answers

What is the meaning of the term 'pyroclastic'?

Fire and rock (B) Signup and view all the answers

Why are pyroclastic flows highly hazardous?

They move at extremely high speeds, making it difficult for people to react in time to avoid harm. (A) Signup and view all the answers

What are some of the hazards created by pyroclastic flows?

Destruction of property by fire and death due to toxic gases (A) Signup and view all the answers

How do pyroclastic surges differ from pyroclastic flows?

Pyroclastic surges travel at faster speeds but typically create damage within a smaller radius than pyroclastic flows. (B) Signup and view all the answers

What is the main reason why pyroclastic surges are more likely to cause death in humans?

The combination of poisonous gases and steam in the pyroclastic cloud can easily suffocate people. (B) Signup and view all the answers

How are tephra different from the solid fragments found in pyroclastic flows?

Tephra are smaller in size and weight compared to solid fragments. (B) Signup and view all the answers

What is the potential hazard associated with tephra, apart from destruction of vegetation and food supplies?

Tephra can generate lightning strikes due to becoming electrically charged. (A) Signup and view all the answers

What is the impact of tephra on respiratory health across a wide geographic region?

Tephra can lead to respiratory diseases due to the thick layers of ash affecting air quality. (A) Signup and view all the answers

In what way do pyroclastic density currents differ from tephra?

Pyroclastic density currents contain fewer solid particles compared to tephra. (A) Signup and view all the answers

What is a volcanic hazard?

Any volcanic process that threatens life or destroys land or infrastructure (A) Signup and view all the answers

What can cause destruction both at the site of a volcanic eruption and miles away?

Tsunamis triggered by volcanic eruptions (A) Signup and view all the answers

How are landslides related to volcanic hazards?

They can occur as a result of volcanic processes and threaten life or destroy land or infrastructure (D) Signup and view all the answers

What is the primary focus when learning about volcanic hazards?

Exploring ways to prevent loss of life through early warning systems (A) Signup and view all the answers

What type of geologic processes can threaten life and destroy property when a volcano erupts?

All of the above (D) Signup and view all the answers

What happens when a volcano erupts with great force and ejects small particles up into the stratosphere?

It renders the area around the volcano uninhabitable (D) Signup and view all the answers

What is one way to prevent the loss of life from volcanic hazards?

Deploying early warning systems (A) Signup and view all the answers

What is the primary cause of landslides associated with volcanic activity?

The injection of magma into volcanic rock (B) Signup and view all the answers

What can volcanic earthquakes trigger according to the text?

Lahars (C) Signup and view all the answers

How do lahars differ from landslides?

Lahars can travel at higher speeds than landslides (A) Signup and view all the answers

What is a defining characteristic of a lahar?

It can contain both volcanic debris and water (B) Signup and view all the answers

What has been established to detect the unique wave frequency of a tsunami?

Technological warning systems (A) Signup and view all the answers

Why is it difficult to prevent the occurrence of a landslide and subsequent tsunami?

There is little that can be done to prevent them (D) Signup and view all the answers

What is the primary focus in preventing the loss of life from tsunamis?

Educating communities in tsunami-prone areas (C) Signup and view all the answers

What causes lahars to be extremely dangerous and destructive for communities?

Their potential to engulf anything in their path (A) Signup and view all the answers