Podcast
Questions and Answers
Which characteristic best describes a dormant volcano?
Which characteristic best describes a dormant volcano?
- Has recently erupted with a high probability of erupting again soon
- Has erupted thousands of years ago with no possibility of eruption
- Exhibits continuous low-level activity with frequent small eruptions
- Has not erupted in a long time, but could erupt in the future (correct)
What constitutes a volcanic risk?
What constitutes a volcanic risk?
- The potential for loss or damage to people and property due to volcanic hazards (correct)
- The visual appeal and geological significance of volcanic landscapes
- The scientific study of volcanoes and their eruptive patterns
- The economic benefits derived from volcanic resources and tourism
An active volcano is defined as one that:
An active volcano is defined as one that:
- is located in a remote, uninhabited area.
- has recently erupted or shows signs of an imminent eruption. (correct)
- has not erupted in historical times.
- shows signs of weathering and erosion.
Approximately how many active volcanoes are estimated to exist worldwide?
Approximately how many active volcanoes are estimated to exist worldwide?
Which of the following is a characteristic of a lahar?
Which of the following is a characteristic of a lahar?
What is ash fall primarily composed of?
What is ash fall primarily composed of?
What distinguishes a pyroclastic flow from other volcanic hazards?
What distinguishes a pyroclastic flow from other volcanic hazards?
Why is tephra fall considered a significant volcanic hazard?
Why is tephra fall considered a significant volcanic hazard?
Which of the following statements accurately describes lava flow in the context of volcanic hazards?
Which of the following statements accurately describes lava flow in the context of volcanic hazards?
In what geological setting are subduction volcanoes typically found?
In what geological setting are subduction volcanoes typically found?
What geological process primarily forms rift volcanoes?
What geological process primarily forms rift volcanoes?
Which geological feature is associated with the formation of hot spot volcanoes?
Which geological feature is associated with the formation of hot spot volcanoes?
Which of the following is NOT a main category of a volcano?
Which of the following is NOT a main category of a volcano?
A volcano is best described as:
A volcano is best described as:
Which of the following characteristics distinguishes an extinct volcano?
Which of the following characteristics distinguishes an extinct volcano?
During a volcanic eruption, what primarily constitutes volcanic gases?
During a volcanic eruption, what primarily constitutes volcanic gases?
A small lahar is characterized by:
A small lahar is characterized by:
Pyroclastic density currents are characterized as:
Pyroclastic density currents are characterized as:
What is the typical speed of pyroclastic flow?
What is the typical speed of pyroclastic flow?
Why are silicic lava flows typically slower than basaltic lava flows?
Why are silicic lava flows typically slower than basaltic lava flows?
Which factor can influence the classification of volcanic hazards, and volcanic risks to the local population??
Which factor can influence the classification of volcanic hazards, and volcanic risks to the local population??
What is a characteristic trait of a Subduction volcano?
What is a characteristic trait of a Subduction volcano?
What role do tectonic plates play in the formation of Rift Volcanoes?
What role do tectonic plates play in the formation of Rift Volcanoes?
Within what type of geological feature do Hot Spot Volcanoes most commonly form, generally?
Within what type of geological feature do Hot Spot Volcanoes most commonly form, generally?
Flashcards
Volcano
Volcano
A mountain or hill, typically conical, having a crater or vent through which lava, rock fragments, hot vapor, and gas are erupted from the Earth's crust.
Active Volcano
Active Volcano
A volcano that has recently erupted or shows signs of erupting soon.
Dormant Volcano
Dormant Volcano
A volcano that has not erupted in a long time but could erupt again in the future.
Extinct Volcano
Extinct Volcano
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Volcanic Hazards
Volcanic Hazards
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Lahar
Lahar
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Ash Fall
Ash Fall
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Pyroclastic flow
Pyroclastic flow
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Volcanic gases
Volcanic gases
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Lava Flow
Lava Flow
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Subduction volcanoes
Subduction volcanoes
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Rift Volcanoes
Rift Volcanoes
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Hot spot volcanoes
Hot spot volcanoes
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Study Notes
Overview
- A volcano is a typically conical mountain or hill
- It has a crater or vent
- Lava, rock fragments, hot vapor, and gas are erupted from the Earth's crust through the crater or vent of a volcano
Three Main Categories of Volcanoes
- Active
- Dormant
- Extinct
Active Volcano
- It has erupted recently
- There is a possibility that it may erupt soon.
Dormant Volcano
- It has not erupted in a long time
- There is a possibility that it might erupt in the future
Extinct Volcano
- It erupted thousands of years ago
- There is no possibility of eruption
Volcanic Hazards
- They are potentially dangerous volcanic processes, such as lava flows, pyroclastic flows, and ash
- A volcanic risk is any potential loss or damage as a result of a volcanic hazard
- This can affect persons or property
- Volcanic risks may negatively impact the productive capacity/sustainability of a population
- There are about 500 active volcanoes throughout the world
- About 50 volcanoes erupt in an average year
Lahar
- A lahar is a hot or cold mixture of water and rock fragments
- It flows down the slopes of a volcano
- Small lahars are less than a few meters wide and several centimeters deep and may flow a few meters per second
- Large lahars are hundreds of meters wide and tens of meters deep and can flow several tens of meters per second
Ash Fall
- A rain of airborne ash resulting from a volcanic eruption
Pyroclastic Flow
- They are heavier-than-air gas-particle emulsions
- They travel across the ground at velocities ranging from 10m/sec to 300 m/sec
- Pyroclastic density currents are gravity-driven, rapidly moving, ground-hugging mixtures of rock fragments and hot gases
- "Pyroclastic surge” is a synonym for “dilute pyroclastic flow"
Tephra Fall and Ballistic Projectiles
- They endanger life and property by the force of impact of falling fragments, but this occurs only close to an eruption
- Loss of agricultural lands can occur if burial is greater than 10cm depth
- They produce suspensions of fine-grained particles in air and water which clogs filters and vents of motors, human lungs, industrial machines, and nuclear power plants
- They carry noxious gases, acids, salts, and, close to the vent, heat
Volcanic Gases
- Gases that are released to the atmosphere during an eruption
- They are also released while the magma lies close to the surface from hydrothermal systems
Lava Flow
- Lava flows rarely threaten human life
- Lava usually moves slowly
- Silicic flows move at a few centimeters per hour and basaltic flows move at several km/hour
Subduction Volcanoes
- Located in the zones of the Earth's crust where one tectonic plate is thrust and consumed beneath another
Rift Volcanoes
- Occur where tectonic plates diverge and are considered effusive
- They especially occur on the deep ocean floor
Hot Spot Volcanoes
- Exist in the middle of tectonic plates where a crustal weakness allows molten material to penetrate from the Earth's interior
- Magma is a complex mixture of silicates which contains dissolved gases and, often, crystallized minerals in suspension
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