Volcanos

Question 1

Huh?

Question 2

Who’s making volcano quesadillas?

Answer 2

Shrek.

Question 3

What is a volcano?

Answer 3

A volcano is a natural crack or vent(opening/fissure) in the earth’s crust that links the surface to the mantle, through which magma (quietly or violently) and other volcanic materials are ejected naturally at intervals.

Question 4

Where can volcanos occur?

Answer 4

At plate margins
On land
Under the sea(on the sea bed)

Question 5

What is the difference between lava and magma?

Answer 5

Magma=molten rock beneath the earth’s surface
Lava=molten rock that erupts or flows out

Question 6

What is a volcanic cone?

Answer 6

A triangle shaped hill or mountain formed as material from volcanic eruptions piles up on the volcanic vent or opening in the earth’s crust

Question 7

What is a vent?

Answer 7

The opening or gap that links the surface with the mantle

Question 8

What is a pipe?

Answer 8

Vertical, hardened lava found within the centre of the volcanic cone

Question 9

What is a side pipe?

Answer 9

A channel that cuts across the volcanic cone through which lava and other volcanic material can escape.

Question 10

What is another name for a side pipe?

Answer 10

A secondary pipe

Question 11

Name 3 volcanos in the Caribbean and where they are located

Answer 11

Any 3 of the following:

Soufrière Hills-Monserrat
Mt St Catherine-Grenada
Norne Trois Piton- Dominica
The Soufrière volcano-St Vincent
Mt Liamuiga- St kitts

Question 12

Name 3 volcanos that exist internationally and where they are located

Answer 12

Mount Etna- Sicily Italy
Fuji Yama-Japan
Cotopaxi-Ecuador,South America
Mount St Helens-USA

Question 13

What does the term ‘active’ in the context of volcanoes mean?

Answer 13

Scientists often consider a volcano to be active if it is showing signs of unrest so the term ‘active volcano’ is best described as one that’s currently in a state of regular eruptions

The term active can only mean in terms of human life spans

Question 14

State 3 early signs that a volcano will erupt.

Answer 14

Any 3 of the following are applicable.
- Earthquake activity
- Gas leaks
- Steam or smoke emerging from vents
- Deviations in local electric and magnetic fields
- Development of new ground cracks or the widening of old ones
- Changes in colour/temperature of mineral deposits
- Swelling or bulging on the sides of the volcano

Question 15

State some instruments used to measure the warning signs of a volcano.

Answer 15

• tilt meter
• infra red instruments

Question 16

Define Primary vs. Secondary hazards.

Answer 16

• Primary hazards: caused to the direct eruption or emissions of a volcano
• Secondary hazards: occur as a result of the eruption or indirect emissions

Question 17

State some primary hazards of a volcano

(Must also know how they occur and how they affect man and his environment)

Answer 17

• lava flows
• pyroclastic flows or pyroclastic surges
• tephra pyroclasts
• Ash falls
• cinder falls
• volcanic bombs
• volcanic gases

Question 18

Give the two types of lava flows, their properties, where they occur and how they can affect man and his environment.

Answer 18

Basic/Basaltic Lava - is free flowing and can move very quickly (~50 km/hr). They are usually emitted at Divergent Plate Boundaries causing massive destruction such as loss of property, roads, vegetation and lives.

Acidic/Viscous Lava - move somewhat slowly but can cause destruction as they erupt violently and emit poisonous gases. They are usually emitted at Convergent Plate Boundaries and can poison people, burn and destroy everything in it part.

Question 19

State what are pyroclastic flows, what are their features ( temp, speed etc.) and how they can be a threat to man.

Answer 19

Pyroclastic flows are mixtures of hot rock fragments, lava particles, and ash buoyed up by hot gases. They move very quickly and faster than lava flows due to the gas content and they bounce and roll down the slope due to the rock composition being high. They can move at ~100 km/hr and can reach temperatures of ~ 200 °C - 800 °C. They can suffocate people, knock down walls, melt things etc.

Question 20

What are pyroclastic surges?

Answer 20

Pyroclastic surges form when a pyroclastic flow loses its rock content, and has an increased speed and buoyancy as the rocks are no longer holding it back. They can exceed 240 km/hr as they have higher gas content which keeps it buoyant as it floats over the surface downhill.

Question 21

What are pyroclastic surges also called?

Answer 21

Pyroclastic surges are also called Nuées Ardentes or glowing clouds.

Question 22

What are tephra/pyroclasts?

Answer 22

Tephra are all types of solid material, including lava and fragmented or shattered volcanic materials (volcanic bombs, cinder and ash)

Question 23

What are Ash falls and how can they affect humans?

Answer 23

Ash refers to rock debris that is broken up by volcanic eruptions and thrown up into the atmosphere. They are less than 2 mm in size and can cause lots of health problems, bury roads and buildings, damage crops and suffocate people.

Question 24

What are cinder falls and how can they affect men?

Answer 24

Cinder falls are rock debris that are broken up by volcanic eruptions and are 2 mm - 64 mm in size. They can cause the same damage as Ash falls as well as concussions, death etc.

Question 25

What are volcanic bombs and its effects on men?

Answer 25

Volcanic bombs are rock debris broken up by volcanic eruptions and they are larger than 64 mm and can reach up to 1 m in diameter. They can cause great damage…

Question 26

What are some volcanic gases released during eruptions and how can they affect man and his environment?

Answer 26

Volcanic gases include water vapour, carbon dioxide , sulphur dioxide, chlorine, hydrogen sulphide, helium, carbon monoxide and hydrogen chloride. The heavier gases like carbon monoxide can be collected in depressions and cause suffocation of people and animals. They can also cause breathing problems or skin and eye irritations.

Question 27

State some secondary hazards of a volcano.

(Must know how they are caused in relation to primary hazards and how they can affect man and his environment)

Answer 27

• acid rain
• mudflows/lahars
• debris avalanches and debris flows
• flooding
• tsunamis
• earthquakes
• atmospheric effects

Question 28

What is acid rain, how is it caused and how can it affect man and his environment?

Answer 28

Acid rain is caused by volcanic gases mixing with rain which can now scorch vegetation, kill aquatic life and contaminate the waters.

Question 29

What are lahars, how is it caused and how can it affect man and his environment?

Answer 29

Lahars are mudflows of volcanic materials. The huge amounts of ash and debris can mix with water and then move rapidly down the slope over long distances. They can be thick water or wet concrete and can remove anything in their paths like bridges, highways and houses.

Question 30

What are debris avalanches, how is it caused and how can it affect man and his environment?

Answer 30

Volcanic mountains can become over steepened as a result of the addition of new materials over time as well as due to inflation of the mountain as magma intrudes. Over-steepened slopes may lead to the area becoming gravitationally unstable, leading to a sudden slope failure that results in landslides, debris slides or debris avalanches when the volcano erupts. Every object in its path that is stationary can have its stability reduced.

Question 31

What is Flooding, how is it caused and how can it affect man and his environment?

Answer 31

1) Drainage systems can become blocked by deposition of pyroclastic flows and lava flows. Such blockage may create a temporary dam that could eventually I’ll with water and fail resulting in floods.

2) volcanoes in cold climates can melt snow, rapidly reading an overwhelming amount of water into the drainage systems.

3) Gases emitted into the atmosphere like steam as well as ash or dust particles can lead to heavy downpour in a short amount of time which can cause flooding

Question 32

What are tsunamis, how is it caused and how can it affect man and his environment?

Answer 32

1) Tsunamis are giant sea waves formed when a volcano erupts and it’s cone collapses creating a caldera falls into a nearby body of water

2) Tsunamis can also be caused due to vibrations set up when volcanoes erupt.

They can drown people and destroy buildings as they move like walls into the land at great speeds

Question 33

What are earthquakes, how is it caused and how can it affect man and his environment?

Answer 33

• Earthquakes associated with volcanoes are the vibrations felt because of the movement of magma within the Earth’s surface. These Earthquakes can be felt before, during and after the eruption, varying in strength. Earthquakes can trigger landslides, which in turn can cause tsunamis. Volcanic earthquakes can destroy infrastructure, settlement, businesses and cover crops and injure and or kill persons.

Question 34

What are the atmospheric effects of volcanoes?

Answer 34

Volcanoes can have a short term effect on the climate from the different things it injects into the atmosphere like ash etc. Volcano ash reflects solar radiation, thus causing temperatures to be cooler for several years after the eruption.

The opposite effect can happen with the gases released, as some gases like CO2 can trap heat and enhance global warming.

Question 35

State and explain 3 negative consequences of volcanic eruptions and state whether the impact is environmental, social, physical or economic.

Answer 35

Any of the following 3
- loss of lives: people can be killed in many ways during volcanic eruptions as they are dangerous. They can be killed directly as lava flows, or injured while moving to safety - social

• loss of revenue and businesses: economic activity can suffer as businesses can be destroyed and agriculture is lost. This can reduce foreign revenue. Economic
• loss of ecosystems: habitats and landscapes are damaged by lava flows. Wildlife, plants and even whole ecosystems can be destroyed. Endangered animals can become extinct. Environmental
• destruction of infrastructure and amenities: roads, electricity, water may be lost or interrupted for a long time. Water sources can become polluted, and communication networks destroyed. Physical
• depopulation: people may be forced to migrate out of the country or move to different parts of the country where it is safe. Families can become separated temporarily or permanently. Areas become abandoned if people don’t return. Social
• pollution: the taxes gases and burning of the vegetation or deposition of ash onto rivers and land can lead to areas becoming polluted uninhabitable by man for a number of years. Environmental
• health problems: dust and ash fall can cause health problems especially to vulnerable individuals like the elderly, babies and people with allergies or lung problems. Hot gases can also irritate the eyes. Social
• enhance global warming: volcanic eruptions give off green house gases that can trap heat and increase the temperature. Environmental

Question 36

State and explain 3 positive consequences of volcanic eruptions and state whether the impact is environmental, social, physical or economic.

Answer 36

Any 3 of the following
- geothermal energy: this is where heat from the earth is used to generate electricity. It can be generated in areas where magma lies close to the surface. Environmental

• fertile soils: ash ejected by the volcano acts as a good fertilizer for soils. After years of weathering and cooling, volcanic soils are very productive. Environmental social economic
• encourages tourism: volcanoes attract many tourists, who enjoy the dramatic scenery of them. The unique landscapes and the erupting lava also attracts them. Economical
• new job opportunities: rising magma brings valuable materials to the surface, creating mining opportunities. Sulfur copper, gold and diamonds can be produced/brought up during an eruption. Economic social
• New land can be created: volcanic eruptions lead to the deposition of rocks and debris which can add materials along the coast or surrounding areas creating new land or altering the shape of places. Environmental
• raw materials for secondary industries: volcanic material can be made into blocks , and a lot of the materials are mined, to make cement and kitchen counters. Economical
• water production: all the water we have on earth was actually produced by volcanoes. It comes out as steam and overtime builds up the water on earth. Water can actually come out of magma itself. Environmental
• Atmospheric cooling: short term benefits, ash and sulphur gas exploded into the atmosphere and combined with water droplets and stayed there for years, cooling the earth. Volcanoes have helped to keep the earth 2-3°C cooler than it otherwise may be. Environmental

Question 37

What are fumaroles and ghauts?

Answer 37

Fumaroles - vents or openings at the surface where volcanic gases and vapour are emitted. They are a common sign on active volcanoes and are a sign that the volcano is active as it indicates heat from volcanic sources.

Ghauts - a small cleft in a hill through which a rivulet runs down to the sea