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Questions and Answers
What occurs when water reaches the surface during volcanic activity?
What occurs when water reaches the surface during volcanic activity?
Which step follows the spinning of a turbine in the process of generating electricity from steam?
Which step follows the spinning of a turbine in the process of generating electricity from steam?
What is the primary purpose of the PHIVOLCS Volcano Alert Level Scheme?
What is the primary purpose of the PHIVOLCS Volcano Alert Level Scheme?
What are monitoring criteria in the context of volcanic alert levels?
What are monitoring criteria in the context of volcanic alert levels?
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What is one of the negative effects of volcanic eruptions mentioned?
What is one of the negative effects of volcanic eruptions mentioned?
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Which alert level indicates the highest severity of unrest in a volcano?
Which alert level indicates the highest severity of unrest in a volcano?
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What should be done following the issuance of volcanic warning recommendations?
What should be done following the issuance of volcanic warning recommendations?
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What is indicated by the step-down criteria in volcanic alert levels?
What is indicated by the step-down criteria in volcanic alert levels?
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What characterizes lava flows composed of low silica magma?
What characterizes lava flows composed of low silica magma?
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Which volcanic hazard involves a mixture of hot gases, ash, and fragmented volcanic particles that rapidly flow down slopes?
Which volcanic hazard involves a mixture of hot gases, ash, and fragmented volcanic particles that rapidly flow down slopes?
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What phenomenon is referred to as the mass failure of a volcano’s flank potentially caused by magma intrusion?
What phenomenon is referred to as the mass failure of a volcano’s flank potentially caused by magma intrusion?
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Which volcanic gas is primarily responsible for the formation of acid rain and can be a significant hazard during eruptions?
Which volcanic gas is primarily responsible for the formation of acid rain and can be a significant hazard during eruptions?
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What is a lahar commonly described as?
What is a lahar commonly described as?
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How can secondary explosions occur in the context of volcanic hazards?
How can secondary explosions occur in the context of volcanic hazards?
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What geological event can ground subsidence and fissuring commonly accompany?
What geological event can ground subsidence and fissuring commonly accompany?
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Which of the following is NOT a principal volcanic gas released during eruptions?
Which of the following is NOT a principal volcanic gas released during eruptions?
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Which type of volcanic eruption is characterized by explosive outbursts that generate pyroclastic flows?
Which type of volcanic eruption is characterized by explosive outbursts that generate pyroclastic flows?
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What is the primary factor that influences the viscosity of magma?
What is the primary factor that influences the viscosity of magma?
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When preparing for a volcanic eruption, which item is essential to include in your emergency kit?
When preparing for a volcanic eruption, which item is essential to include in your emergency kit?
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What distinguishes Hawaiian eruptions from Icelandic eruptions?
What distinguishes Hawaiian eruptions from Icelandic eruptions?
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Which of the following is a precautionary measure to take before a volcanic eruption?
Which of the following is a precautionary measure to take before a volcanic eruption?
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Which type of eruption is considered the most explosive?
Which type of eruption is considered the most explosive?
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What is a common misperception about gas content in relation to volcanic eruptions?
What is a common misperception about gas content in relation to volcanic eruptions?
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Which of the following items is not typically recommended for the emergency evacuation plan?
Which of the following items is not typically recommended for the emergency evacuation plan?
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Study Notes
Lava Flows
- Lava flows composed of low silica magma have low viscosities and flow at high speeds (kilometers per hour)
Volcanic Hazards
- Tephra (Ashfall): Tephra (fragmented volcanic particles) or ash (particles less than 2 mm in diameter) are propelled through the atmosphere and fall downwind, forming blankets of tephra fall or ashfall.
- Pyroclastic Density Currents (PDCs): Mixtures of fragmented volcanic particles, hot gases, and ash that rush down volcanic slopes or outward from a vent at high speeds.
- Lateral Blasts: Laterally-directed thrusts of hot gas and ash generated from an exploding dome on the summit vent or inside the edifice when the volcanic flanks fail.
- Volcanic Gas: Gases dissolved in magma are released during eruptions. The principal volcanic gases are water vapor, hydrogen sulfide, sulfur dioxide, carbon dioxide, carbon monoxide, hydrogen chloride, and hydrogen fluoride.
- Lahar: Slurries of volcanic sediment, debris, and water that cascade down volcano slopes through rivers and channels.
- Debris Avalanche (Sector Collapse): Mass failure of the flanks of a volcano edifice due to magma intrusion, earthquakes, or fault movements beneath the edifice.
- Ground Subsidence and Fissuring: Ascending magma can cause fissures in the ground, typically along fractures or faults. Magma removal can lead to ground subsidence and further fissuring, often accompanied by earthquakes.
- Secondary Explosions, PDCs, and Ashfall: Secondary explosions can occur when hot volcanic deposits come into contact with water leading to small-scale PDCs and minor ashfall.
Factors Affecting Volcanic Eruption
- Viscosity: Fluid's resistance to flow
- Gas Content: The amount of dissolved gases in magma
- Magma Composition (Silica Content): The higher the silica content, the more viscous the magma
Types of Volcanic Eruption
- Icelandic/Hawaiian: Massive amounts of very hot, thin, runny lava flooding the Earth's surface, with the main difference being that Hawaiian eruptions primarily erupt from the summit vent.
- Strombolian: Short-lived explosive eruptions shooting thick, pasty lava, steam, and gas into the air.
- Vulcanian: More violent and explosive than Strombolian eruptions, containing high dark clouds of steam, ash, and gas.
- Pelean: Explosive outbursts generating pyroclastic flows, dense mixtures of hot volcanic fragments and gas.
- Plinian: The most explosive type, characterized by powerful eruptions that send ash high into the atmosphere.
Preparing for a Volcanic Eruption
- Develop evacuation and shelter plans: Ensure everyone understands them.
- Prepare necessary supplies: Flashlight with extra batteries, first aid kit, emergency food and water, manual can opener, essential medicines, sturdy shoes, respiratory and eye protection, a battery-powered radio.
- Follow authorities' instructions: Tune in to radio/television for volcano updates, listen to disaster sirens.
- Gather emergency supplies: Pack a 1-week supply of prescription medications.
- Prepare an emergency kit for your vehicle: Include food, flares, booster cables, maps, tools, a first aid kit, a fire extinguisher, sleeping bags, flashlight, batteries, etc.
- Fill your vehicle's gas tank
Geothermal Power Plant
- Energy generation: Water is pumped into the earth where it's heated by geothermal energy.
- Water turns to steam: When the water reaches the surface, the drop in pressure causes it to turn into steam.
- Steam spins a turbine: The spinning turbine drives a generator to produce electricity.
- Cooling tower cools the steam: The steam condenses back into water.
- Water is pumped back into the earth: The cooled water is pumped back into the earth to continue the process.
Positive Effects of Volcanoes
- Creates spectacular scenery
- Produces rich soil for farming
- Can cause a decrease in Earth's surface temperature
- People become creative, using ashfall to make earthenware
Negative Effects of Volcanoes
- Causes loss of lives
- Damages properties
- Causes air pollution
- Causes water pollution
Taal Volcano Alert Level Scheme (PHIVOLCS)
- Alert Level: Represents the overall condition of the volcano, with levels 1-5 indicating increasing severity of unrest.
- Monitoring Criteria: Parameters from instrumental, visual, and sensory observations acquired by Volcano Observatories.
- Interpretation: Explaining the probable processes within the volcano based on monitoring criteria and potential dangers.
- Recommendations: Response measures for public safety, implemented by local and national government units.
- Step-Down Criteria: Conditions needed to lower the alert level.
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Description
Explore the various volcanic hazards including lava flows, tephra, pyroclastic density currents, and volcanic gases. This quiz will test your understanding of how these phenomena occur and their impacts on the environment. Prepare to dive into the dynamics of volcanic activity and its hazards.
