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?

Mt. Pinatubo (D) Signup and view all the answers

What type of eruption is characterized by fountain lava?

Strombolian (C) Signup and view all the answers

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

Caldera (A) Signup and view all the answers

Which of the following best describes a dormant volcano?

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

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

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

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

Phreatic or Hydrothermal (A) Signup and view all the answers

What distinguishes a phreatomagmatic eruption from a phreatic eruption?

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

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

The Hawaiian Islands (B) Signup and view all the answers

What can occur following the collapse of a volcano?

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

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

On top of an extinct volcano (C) Signup and view all the answers

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

Magma (B) Signup and view all the answers

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

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

What characteristic is most closely associated with a stratovolcano?

A steep, conical profile (B) Signup and view all the answers

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

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

Which of the following best describes a caldera?

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

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

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

Mauna Kea is characterized as which type of volcano?

Shield volcano (B) Signup and view all the answers

What is a common characteristic of eruptions from shield volcanoes?

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

Which volcanic hazard is capable of generating tsunamis?

Undersea eruptions or debris avalanches (D) Signup and view all the answers

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

Sulfur dioxide (SO2) (C) Signup and view all the answers

What are the causes of lahar?

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

Which of the following best describes 'tephra'?

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

What is the primary driving force behind pyroclastic flows?

Gravitational force (A) Signup and view all the answers

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

Lahars (C) Signup and view all the answers

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

Mount Pinatubo (B) Signup and view all the answers

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

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

What is a significant danger associated with tephra falls?

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

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

Alert Level 5 (B) Signup and view all the answers

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

An area where permanent habitation is not recommended due to constant volcanic risks. (C) 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?

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

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

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

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

Pyroclastic flows (D) Signup and view all the answers

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

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

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

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

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

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

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

Alert Level 3 (B) Signup and view all the answers

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

Seek shelter right away. (A) Signup and view all the answers

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

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

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

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

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

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

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

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

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

Remove the ash immediately. (D) Signup and view all the answers

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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Description

This quiz covers disaster preparedness related to volcanic eruptions, explaining the distinctions between active, dormant, and extinct volcanoes. Learn about the various volcanic hazards including tsunamis and toxic gases that can impact communities. Prepare yourself with knowledge that contributes to better risk reduction strategies.