Disaster Readiness Week 6

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Questions and Answers

Which eruption type is characterized by a tall column reaching up to 20 km high, accompanied by pyroclastic flow and ash fall tephra?

  • Plinian
  • Phreatomagmatic
  • Vulcanian (correct)
  • Strombolian

The eruption of Mt. Fukutoku-Okanoba is characterized by:

  • Fountain lava and periodic weak to violent eruption
  • Tall eruption columns reaching up to 20 km
  • Excessively explosive gas and pyroclastics
  • A large column of fine ash, high speed and side-way emission of pyroclastics (correct)

Which Philippine volcano has erupted the most times since records have been kept?

  • Mt. Kanlaon
  • Mt. Mayon (correct)
  • Taal Volcano
  • Mt. Bulusan

Which of the following volcanoes experienced Plinian type of eruption?

<p>Mt. Pinatubo (D)</p> Signup and view all the answers

What type of eruption is characterized by fountain lava?

<p>Strombolian (C)</p> Signup and view all the answers

What geological feature is most commonly associated with an emptied magma chamber and subsequent sinking of the ground?

<p>Caldera (A)</p> Signup and view all the answers

Which of the following best describes a dormant volcano?

<p>A volcano that is currently inactive but could potentially erupt in the future (A)</p> Signup and view all the answers

What geological process is primarily responsible for the formation of volcanoes at subduction zones?

<p>The partial melting of a subducting plate which forms magma (A)</p> Signup and view all the answers

Which type of volcanic eruption is characterized by the interaction of hot rocks coming in contact with water?

<p>Phreatic or Hydrothermal (A)</p> Signup and view all the answers

What distinguishes a phreatomagmatic eruption from a phreatic eruption?

<p>Phreatomagmatic eruptions are driven by the contact between magma and water, while phreatic eruptions are caused by hot rocks contacting water (D)</p> Signup and view all the answers

Which is an example of a volcano formed by a tectonic plate moving over a hot spot?

<p>The Hawaiian Islands (B)</p> Signup and view all the answers

What can occur following the collapse of a volcano?

<p>The formation of supervolcanoes in the event of acidic magma (B)</p> Signup and view all the answers

Where is Edinburgh Castle located, in relation to volcanic activity?

<p>On top of an extinct volcano (C)</p> Signup and view all the answers

What is the primary material emitted from a volcano during an eruption?

<p>Magma (B)</p> Signup and view all the answers

Which of the following best describes the formation of a shield volcano?

<p>Built from layers of lava resulting from continual eruptions (D)</p> Signup and view all the answers

What characteristic is most closely associated with a stratovolcano?

<p>A steep, conical profile (B)</p> Signup and view all the answers

How does the viscosity of lava differ between shield and stratovolcanoes?

<p>Shield volcanoes have low viscosity lava, while stratovolcanoes have high viscosity lava flows (D)</p> Signup and view all the answers

Which of the following best describes a caldera?

<p>A crater formed by the explosion of a stratovolcano's top (A)</p> Signup and view all the answers

The magma that forms the lava in stratovolcanoes is often described as:

<p>Felsic, with high to intermediate levels of silica (B)</p> Signup and view all the answers

Mauna Kea is characterized as which type of volcano?

<p>Shield volcano (B)</p> Signup and view all the answers

What is a common characteristic of eruptions from shield volcanoes?

<p>Lava flows that spread over a wide area (A)</p> Signup and view all the answers

Which volcanic hazard is capable of generating tsunamis?

<p>Undersea eruptions or debris avalanches (D)</p> Signup and view all the answers

Which of the following volcanic gases is known to be irritating to the eyes, skin, and respiratory system?

<p>Sulfur dioxide (SO2) (C)</p> Signup and view all the answers

What are the causes of lahar?

<p>Intense rainfall during typhoons, monsoons, and thunderstorms (D)</p> Signup and view all the answers

Which of the following best describes 'tephra'?

<p>All sizes of rock fragments and lava blobs ejected into the atmosphere. (C)</p> Signup and view all the answers

What is the primary driving force behind pyroclastic flows?

<p>Gravitational force (A)</p> Signup and view all the answers

Which of the following can cause the blocking of tributary streams and subsequent formation of a lake?

<p>Lahars (C)</p> Signup and view all the answers

What is considered the second largest volcanic eruption of the twentieth century as detailed in the content?

<p>Mount Pinatubo (B)</p> Signup and view all the answers

What is the primary purpose of hazard maps in relation to volcanic activity?

<p>To delineate areas at risk from various volcanic hazards. (B)</p> Signup and view all the answers

What is a significant danger associated with tephra falls?

<p>Disruption to land and air transportation, water, and power supply (C)</p> Signup and view all the answers

Which alert level indicates the highest risk, with a hazardous eruption ongoing?

<p>Alert Level 5 (B)</p> Signup and view all the answers

What does a 'Permanent Danger Zone' (PDZ) signify in the context of volcano preparedness?

<p>An area where permanent habitation is not recommended due to constant volcanic risks. (C)</p> Signup and view all the answers

What is a key recommendation people should follow in terms of long-term development planning, according to the content?

<p>Consulting volcano hazard maps before choosing sites for development to avoid high-risk areas (D)</p> Signup and view all the answers

What does 'Alert Level 2' indicate about a volcano's condition?

<p>The volcano shows increasing unrest, likely of magmatic origin, with a potential for eruption. (A)</p> Signup and view all the answers

Besides lava flows, what other type of ground-based volcanic impact can hazard maps help illustrate?

<p>Pyroclastic flows (D)</p> Signup and view all the answers

Before a volcanic eruption, what is the most important action regarding family emergency plans?

<p>Confirm the plan considers community alert levels and recommended actions. (A)</p> Signup and view all the answers

What is the most important action to take before a volcanic eruption?

<p>Determine the distance of your location from the volcano. (B)</p> Signup and view all the answers

During a volcanic eruption, what is the recommended action regarding vehicle use?

<p>Keep windows up and avoid using the air conditioning. (D)</p> Signup and view all the answers

At what alert level would you expect magma to have moved close to the crater?

<p>Alert Level 3 (B)</p> Signup and view all the answers

What should you do immediately if caught in an ash or tephra fall?

<p>Seek shelter right away. (A)</p> Signup and view all the answers

During a volcanic eruption, what precautionary measure should be taken regarding household appliances?

<p>Turn off all electric fans and air conditioning units. (C)</p> Signup and view all the answers

What is the safest approach to drinking water during a volcanic eruption?

<p>Use tap water and boil it before consuming. (A)</p> Signup and view all the answers

After a volcanic eruption, when is it safe for families to return home?

<p>Once local authorities declare it safe. (C)</p> Signup and view all the answers

What action should be taken regarding ash fall during an eruption?

<p>Avoid cleaning or shoveling ash during eruptions. (B)</p> Signup and view all the answers

If living near a volcano what should be the first action after an ash fall stops?

<p>Remove the ash immediately. (D)</p> Signup and view all the answers

Flashcards

Volcano

A mountain where lava comes from a magma chamber.

Magma

Hot, liquid rock located beneath the Earth's surface.

Shield Volcano

A type of volcano with broad, gently sloping sides made from fluid lava flows.

Stratovolcano

A tall, conical volcano built of layers of hardened lava and ash, often explosive.

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Caldera

A large crater formed after a volcano erupts and collapses.

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Basalt

A type of rock formed from cooled lava, often found in shield volcanoes.

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Tephra

Fragments of volcanic rock and ash ejected during an eruption.

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Viscosity

A measure of a fluid's thickness; high viscosity means stickier lava.

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Phreatomagmatic Surge

A phenomenon of ash and pyroclastics during volcanic eruptions, observed in eruptions like Mt.Fukutoku-Okanoba.

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Strombolian Eruption

A type of eruption characterized by weak to violent lava fountains, exemplified by Mt.Irazu in Costa Rica.

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Vulcanian Eruption

An eruption characterized by tall columns of ash and pyroclastic flow, reaching up to 20 km high, like Mt.Paricutin in Mexico.

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Plinian Eruption

An extremely explosive volcanic eruption that releases gas and pyroclastics, with examples like Mt.Pinatubo.

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Active Volcanoes in the Philippines

Includes Mt.Mayon, Taal Volcano, and others, with defined last erupted times and historical eruptions.

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Collapsed Volcanoes

Volcanoes that have emptied their magma chambers and sunk, often forming lakes.

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Caldera Volcanoes

A large volcanic crater formed by a major eruption, resulting in the collapse of the volcano.

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Active Volcanoes

Volcanoes that are currently erupting or have erupted in the last 10,000 years.

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Dormant Volcanoes

Volcanoes that are currently inactive but have the potential to erupt again in the future.

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Extinct Volcanoes

Volcanoes that have not erupted in the past 10,000 years and are unlikely to erupt again.

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Subduction Process

The process when one tectonic plate moves under another, leading to magma formation.

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Phreatic Eruption

A steam-driven eruption occurring when hot rocks contact water.

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Phreatomagmatic Eruption

A violent eruption caused by the interaction of water and magma.

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Pinatubo

The 2nd largest volcanic eruption of the 20th century, located in Zambales, Philippines.

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Volcanic Gas

Gases released during eruptions that can be toxic, affecting vegetation and human health.

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Carbon Dioxide (CO2)

A volcanic gas that can be lethal in low-lying areas, posing threats to people and animals.

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Lahar Hazard

A destructive flow of volcanic sediments and water, often triggered by intense rainfall.

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Ballistic Projectiles

Large rock fragments ejected with great force during a volcanic eruption.

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Pyroclastic Flow

A fast-moving, high-density mix of hot gas, ash, and lava from a volcanic eruption.

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Ash Fall

Falling ash that can harm health, disrupt communities, and damage infrastructure.

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Volcanic Alert Levels

A system categorizing the activity level of a volcano, informing public actions.

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Family Emergency Plan

A predetermined strategy for families to follow during emergencies, such as volcanic eruptions.

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Evacuation Areas

Designated locations for people to go during a volcanic eruption for safety.

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Safety During Eruption

Actions to take during a volcanic eruption, such as staying indoors and listening to updates.

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Protective Measures for Ash Fall

Actions like closing windows and wearing masks to prevent ash inhalation.

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Cook Food Thoroughly

Ensuring all food is cooked well post-eruption to avoid illness from contaminated ash.

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House Inspection After Eruption

Recommendation that only adults inspect homes for safety after evacuation.

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Cleaning Up Ash Fall

Immediate removal of ash from surfaces after it has settled to prevent damage.

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Alert Level 0

No alert indicating a quiet volcano with no imminent eruption.

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Alert Level 1

Low level unrest indicating that no eruption is imminent, but unusual activity is present.

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Alert Level 2

Moderate unrest indicating increasing volcanic activity, possibly leading to an eruption.

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Alert Level 3

High unrest indicating magma is near the crater, increasing the chance of an eruption.

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Alert Level 4

Intense unrest signaling that a hazardous eruption is possible within days.

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Permanent Danger Zone (PDZ)

An area around a volcano where permanent habitation is not recommended due to hazards.

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Hazard Maps

Maps that show potential volcanic hazards like lava flows and ash fall, indicating safe and dangerous areas.

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Volcanic Preparedness

Actions taken to mitigate risks before, during, and after a volcanic eruption to ensure safety.

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Study Notes

Disaster Readiness and Risk Reduction (Week 6)

  • Disaster preparedness includes actions taken before, during, and after a volcanic eruption.
  • Volcanoes are mountains where lava (hot, liquid rock) comes from a magma chamber under the ground.
  • Most volcanoes have a volcanic crater at the top.
  • Active volcanoes may erupt again at any time.
  • Dormant volcanoes are currently quiet but could erupt in the future.
  • Extinct volcanoes have not erupted in historical times.

Volcanic Hazard

  • Tsunami: Sea waves generated by sudden displacement of water during underwater eruptions or debris avalanches.
  • Volcanic Gas: Gases released by volcanoes can be concentrated and toxic to vegetation and people.
    • Carbon dioxide (CO2): Trapped in low-lying areas, can be lethal.
    • Sulfur dioxide (SO2): Irritating to eyes, skin, and respiratory system.
    • Hydrogen sulfide (H2S): Very toxic in high concentrations.
    • Hydrogen halides (HF, HCl, HBr): Strong, toxic acids.
  • Ashfall: Harmful to human health, especially those with respiratory or cardiac problems.
    • Causes disruption to land and air transportation, water and power supply, communications, drainage canals and sewerage.
    • Damages buildings, agriculture, and wildlife.
  • Lahars: Flowing thick mixture of volcanic sediments and water.
    • Often triggered by intense rainfall during typhoons, monsoons, and thunderstorms.
    • Can destroy by impact on bridges, roads, houses.
    • Can create a lake that can eventually flood.
  • Tephra Falls and Ballistic Projectiles:
    • Includes all sizes of rock fragments and lava blobs ejected into the atmosphere.
    • Accumulate as deposits.
    • Larger fragments are hurled with great force from the volcano.
  • Pyroclastic Flow: A high-density mix of hot lava blocks, ash and gas that propels pyroclastic debris and moves down hills.

Types of Volcanoes

  • Shield Volcanoes: Built out of layers of lava from continual eruptions.
    • Lava is fluid, spreading over a wide area
    • Have gently sloping sides.
    • Example is Mauna Kea, Hawaii (tallest mountain on Earth when measured from its base on the ocean floor).
  • Stratovolcanoes (Composite Volcanoes): Tall, conical volcanoes
    • Built up of many layers of hardened lava, tephra, pumice, and ash
    • Have steep profiles.
    • Have periodic eruptions.
    • Lava is sticky/ high viscosity.
  • Caldera Volcanoes: Formed when a huge stratovolcano blows its top off
    • The magma chamber empties and the ground sinks.
    • Example is Krakatoa.

Volcano Preparedness

  • Alert Levels: A system used in the Philippines (with variations) to indicate the level of volcanic unrest and impending eruption.
    • Level 0: No alert.
    • Level 1: Abnormal (low level unrest).
    • Level 2: Increasing unrest (moderate unrest).
    • Level 3: Increasing tendency towards eruption.
    • Level 4: Hazardous eruption imminent (intense unrest).
    • Level 5: Hazardous eruption (ongoing).
  • Permanent Danger Zone (PDZ): Delineated and identified where no permanent habitation is recommended due to possible impact of hazards at any time.
  • Hazard Maps: Illustrate potential impacts—lava flows, pyroclastic flows, ash fall, volcanic gases, and lahars in valleys that drain the volcano.
    • Help understand affected areas/ safe areas.
  • Before, During, and After: Actions to take before, during, and after a volcanic eruption.
    • Before: Consult hazard maps, be aware of hazards, and have a family emergency plan.
    • During: Stay inside, listen to radio, do not drive through ash, and do not try to clean ash.
    • After: Listen to updates, thoroughly cook food if necessary and go home only when local authorities say it is safe.
  • Cleaning Up Ashfall: Wear a mask, lightly damp the ash for cleaning, and do not dump ash into sewage systems.

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