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Questions and Answers
What is a defining characteristic of a shield volcano?
What is a defining characteristic of a shield volcano?
Which type of volcanic material is categorized as lapilli?
Which type of volcanic material is categorized as lapilli?
What effect can erupted sulfur have on the environment?
What effect can erupted sulfur have on the environment?
What is a caldera formed from?
What is a caldera formed from?
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How do lava tubes form during a volcanic eruption?
How do lava tubes form during a volcanic eruption?
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What is a primary characteristic of vents in volcanic eruptions?
What is a primary characteristic of vents in volcanic eruptions?
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Which of the following correctly describes geysers?
Which of the following correctly describes geysers?
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What is a jokulhlaup and how is it generated?
What is a jokulhlaup and how is it generated?
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Which of the following is characteristic of hot springs?
Which of the following is characteristic of hot springs?
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What defines pyroclastic sheet deposits?
What defines pyroclastic sheet deposits?
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What is magma called once it reaches the Earth's surface?
What is magma called once it reaches the Earth's surface?
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Which factor primarily controls the viscosity of magma?
Which factor primarily controls the viscosity of magma?
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Approximately how many volcanoes erupt each year?
Approximately how many volcanoes erupt each year?
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Where are two-thirds of all active volcanoes located?
Where are two-thirds of all active volcanoes located?
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What determines the type of volcano that forms in a specific area?
What determines the type of volcano that forms in a specific area?
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How many people approximately live in the vicinity of volcanoes?
How many people approximately live in the vicinity of volcanoes?
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What is the result of volcanic eruptions in sparsely populated areas?
What is the result of volcanic eruptions in sparsely populated areas?
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Which of the following is NOT a type of tectonic setting associated with volcanoes?
Which of the following is NOT a type of tectonic setting associated with volcanoes?
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Which of the following crops thrive in volcanic soil?
Which of the following crops thrive in volcanic soil?
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What type of energy can be generated from volcanic activity?
What type of energy can be generated from volcanic activity?
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What is one reason people are attracted to live near volcanoes?
What is one reason people are attracted to live near volcanoes?
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Which of the following is NOT included in the monitoring of volcanoes?
Which of the following is NOT included in the monitoring of volcanoes?
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What significant natural service function does volcanic activity contribute to?
What significant natural service function does volcanic activity contribute to?
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What event triggered the lateral blast at Mt. St. Helens on May 18, 1980?
What event triggered the lateral blast at Mt. St. Helens on May 18, 1980?
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What was one major consequence of the lateral blast at Mt. St. Helens in 1980?
What was one major consequence of the lateral blast at Mt. St. Helens in 1980?
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Which gas is odorless and can displace breathable air during a volcanic eruption?
Which gas is odorless and can displace breathable air during a volcanic eruption?
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What defines a lahar in the context of volcanic hazards?
What defines a lahar in the context of volcanic hazards?
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What was the estimated damage cost from the Mt. St. Helens event in 1980?
What was the estimated damage cost from the Mt. St. Helens event in 1980?
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Which of the following is NOT a reason why people live near volcanoes?
Which of the following is NOT a reason why people live near volcanoes?
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What role do earthquakes commonly play in volcanic activity?
What role do earthquakes commonly play in volcanic activity?
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How can volcanic ash affect the climate temporarily?
How can volcanic ash affect the climate temporarily?
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Study Notes
Volcanic Processes and Hazards
- 50 to 60 volcanoes erupt each year
- Most eruptions occur in sparsely populated areas
- Nearly 100,000 people have been killed by volcanic eruptions in the past 100 years
- 500 million people live in the vicinity of volcanoes
- Volcanoes are not randomly distributed
- ⅔ of all active land volcanoes are located along the Ring of Fire
- Tectonic setting determines the type of volcano
- Molten rock material below the Earth's surface is called magma
- Magma becomes lava when it reaches the surface
- The viscosity of magma is controlled primarily by silica content
Shield Volcanoes
- Komatiite lava flows
- Very low profile, thin shape
- Non-explosive eruptions
- Found around plate boundaries
Cinder Volcanoes
- Erupt pyroclastic material
- Steep cone shape
- Non-explosive eruptions
- Found around vents, cracks, and fissures
Pyroclastic Materials
- Pyroclastic material are magma fragments explosively ejected by volcanoes
- Ash is less than 2 mm
- Lapilli is 2-64 mm
- Bombs are partially molten and greater than 64 mm
- Blocks are solid and greater than 64 mm
Volcanic Gases
- Primarily water vapor, with lesser amounts of carbon dioxide, nitrogen, sulfur dioxide, and hydrogen sulfide
- Erupted Sulfur can have widespread effects on climate
Calderas
- Formed by explosions or collapse of a volcano's top
- Thousands of meters across and hundreds of meters deep
Lava Tubes
- Form when the flow's margins and upper surface solidify
- Can move up to 50 km/hr
- Can drain and become empty tunnels
Vents
- Any opening for lava and debris
- Can produce flood basalts
Hot Springs
- Heated by hot rocks that heat groundwater, discharged at the surface
Geysers
- Groundwater boils and erupts steam at the surface
Pyroclastic Sheet Deposits
- Huge, sheet-like eruptions of pyroclastic material
Jokulhlaups
- Eruptions that occur beneath or against glaciers
- Rapidly melt ice, producing huge floods
- Examples include Iceland and Mt. Garibaldi
Volcanic Hazards
- The most dangerous manifestations of volcanoes are pyroclastic flows (nuee ardentes)
Lateral Blasts
- Rock fragments, gas, and ash blown horizontally from the side of a volcano
- Example: Mt. St. Helens in 1980
Poisonous Gases
- Gas emissions often accompany lava and ash
- Can be emitted alone
- Examples include: Carbon Dioxide (odorless and can displace breathable air), Sulfur Dioxide (odorous and can cause acid rain)
Lahars
- Occur when large amounts of loose volcanic ash and other pyroclastic material become saturated with water and rapidly move down slope
Linkages Between Volcanoes and Other Hazards
- Earthquakes: Can precede or accompany volcanic eruptions
- Landslides: Sector collapses can cause tsunamis (if they enter water)
- Fire: Lava can ignite plants and structures
- Climate Change: Volcanic ash can temporarily cool climate
Why People Live Near Volcanoes?
- Birthplace
- Unaware of risks
- Limited economic ability to move
- Believe eruptions are unlikely
- Fertile land for farming
- Only available land (on some islands, all land is volcanic)
Natural Service Functions
- Volcanic Soil: Good for coffee, maize, pineapples, sugar cane, and grapes
- Geothermal Energy: Creates energy for nearby urban areas
- Mineral Resources: Gold, silver, and nonmetallic rocks (used for soap, building stone, aggregate for roads, railroads, etc.)
- Recreation: Health spas, hot springs, hiking, snow sports, education
- Land Creation: Hawaiian Islands
Volcanic Monitoring and Forecasting
- Monitoring involves recording physical and chemical changes at volcanoes
- Tiltmeters and geodimeters detect changes to slope elevation and shape
- Seismometers detect harmonic tremors
- Gas emissions, thermal, magnetic, and hydrologic monitoring are also measured
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Description
Test your knowledge on volcanic processes and the various types of volcanoes. This quiz covers essential concepts such as magma formation, eruption types, and the dangers posed by volcanic activity. Understand how tectonic settings influence volcanic behavior and explore the characteristics of shield and cinder volcanoes.
