Earthquakes & Volcanos

Question 1

What is the plate tectonics theory?

Answer 1

The lithosphere is divided into several plates known as tectonic plates. the heat from the core causes convection currents in the mantle. This pushes the tectonic plates which float on the mantle

Question 2

Why is the tectonics theory unproven yet

Answer 2

It is too hot for us humans to be so far down near the magma. We also do not have the equipment to drill down that far

Question 3

What clues do we have that support the plate tectonics theory

Answer 3

• Earthquakes and volcanos, we believe these happen because of the seismic energy released when tectonic plates interact
• Pangea, scientists belive that all the continents were originally stuck together to make one supercontinent, Pangea, which is shown when the continents look like pieces of a jigsaw puzzle with each other

Question 4

What is a plate boundary?

Answer 4

A place where two tectonic plates meet

Question 5

What usually happens on plate boundaries

Answer 5

one plate boundaries there tends to be a lot of seismic activities such as earthquakes and volcanos forming

Question 6

What is the most noticeable area for seismic activity? why is there more seismic activity than usual

Answer 6

The Ring of Fire is located in between Asia, Oceania, and America. there is a significant amount of seismic activity here because there are lots of plates interacting with each other

Question 7

What are the layers of earth in order of the inner to outer

Answer 7

Inner core, Outer core, mantle, lithosphere, crust

Question 8

What are the 4 boundary types?

Answer 8

Constructive
Destructive (continental + oceanic)
Destructive (both continental)
Conservative

Question 9

What is a constructive plate boundary and what are the characteristics associated with it?

Answer 9

• When two plates move away from each other, magma shoots up.
• Causes volcanos
• Causes weak earthquakes

Question 10

What is a destructive plate boundary (continental + oceanic) and what are the characteries and what are the characteristics associated with it?

Answer 10

When two plates move towards each other. The oceanic plate is more dense so it will sink under the continental. the area where the two plates collide is called a subduction zone, which is very dangerous.
- causes very dangerous earthquakes
- causes volcanos

Question 11

What is a destructive plate boundary (both continental) and what are some of the characteristics associated with it

Answer 11

Two plates move towards each other. they’re the same density so the crust rises. this creates a convergence zone (range of mountains).
- Doesn’t cause volcanos
- Causes earthquakes

Question 12

What is a conservative plate boundary?

Answer 12

Plae boundaries move side by side. this causes friction which is then released by seismic energy
- Doesn’t cause volcanos
- Causes earthquakes

Question 13

What are the two ways of measuring earthquakes?

Answer 13

Richter scale
Mercalli scale

Question 14

Describe the Richter scale

Answer 14

The Richter scale is the most popular way of measuring seismic activity. it uses a logarithmic sequence to measure seismic activity on a scale of 1 to 10

Question 15

Describe the Mercalli scale

Answer 15

The Mercalli scale is a newer way to measure seismic activity. it’s based on observable earthquake damage, whilst this is easier to fill out it is also less valid because everyone has different interpretations, making the Richter scale still the beter option

Question 16

Christchurch earthquake

Answer 16

FINISH

Question 17

What is a volcano?

Answer 17

A volcano is a mountain or hill, having a vent or crater in which hot molten magma (Lava) molten rock and ash are erupted onto land

Question 18

Outline the parts of a volcano and describe what they are

Answer 18

magma chamber
- this is where the molten rock is stored beneath the ground

main vent
- this is the channel through which
magma
travels to reach the Earth’s surface

secondary vent
- some magma may escape through the side of the volcano, particularly if the main vent becomes blocked

crater
- this is found at the top of the volcano, where the magma erupts from

layers of ash and lava
- Volcanic materials deposited on the sides of volcanos during eruptions, eventually building up the volcano and forming a volcanic comb

Parasitic cone
- smaller volcanic cone that forms on the sides of a larger volcano. it’s created by eruptions from secondary vents, drawing magma away from the main vent

Question 19

What are volcanic bombs, ash, lava, and gas

Answer 19

All are ejected from a volcano during a volcanic eruption

Volcanic bomb
- large rock fragments

Ash
- small particles of rock and glass

Lava
- Magma released out of the earths crust

Volcanic gasses
- Water vapor, Carbon dioxide, and other gases that are released from a volcano, that contribute to atmospheric changes

Question 20

What are the three states of a volcano and explain them all

Answer 20

Extinct - haven’t erupted in millions of years and isn’t expected to erupt again
Dormant - haven’t erupted for a significant period of time such as a decade but is expected to erupt again in the future
Active - has a recent history of eruptions and is expected to erupt in the near future

Question 21

What are the two types of volcanos and outline their features

Answer 21

Shield volcano
- Form on a constructive plate boundary
- runny lava with low viscosity
- gently sloping sides + wide base
- Basaltic magma

Composite volcano
- Forms on a destructive plate boundary
- viscous lava
- steep sides + narrow base
- Layers of thick lava + ash on the side of the volcano

Question 22

Define primary and secondary volcanic hazards

Answer 22

Primary volcanic hazards are the first and direct results of a volcanic eurption

Secondary volcanic hazards the second and knock on effect results of a volcanic eruption

Question 23

Outline 4 primary hazards of a volcanic eruption

Answer 23

Pyroclastic flows - a mixture of rock fragments, gas, and ash that travels rapidly away from a volcanic vent

Lava - Magma that has risen from the earth’s core, which spews out of a volcano and burns everything in its way

Ashfall - Ash falls all over the ground due to prevailing winds, damaging/getting in the way of infrastructure

Volcanic gases - Gases released from a volcano that have detrimental impacts on the surrounding environment, E.G sulfur dioxide causing acid rain

Question 24

Outline 4 secondary hazards of a volcanic eruption

Answer 24

Tsunami - Large water displacement from a volcanic eruption causes large waves.
Landslides - Volcanic cones are weaker after a volcanic eruption causing lots of rocks to fall.
Disease - volcanic materials could damage water filtration systems meaning many would get infected
Lahars - mixture of mud and volcanic ash that flows violently after rainfall

Question 25

Why might people live near a volcano

Answer 25

• Lots of people live near volcanos because of the opportunities they offer:

Volcanic ash makes soils very fertile, leads to job opportunities in agriculture for the area

Many volcanos are visited by tourists, leads to tourist job opportunities

It is a nice volcano and possible extinct so you want to live there with the view (mount fuji - Japan)

People continue to live on slopes of very dangerous volcanos to extract minerals such as sulphur (Indonesia)

Access to geothermal energy

• There are also some other factors:

Many people don’t go far from where they are born, so people were born there and choose not to emigrate.

Poverty, people are living in a L.I.C. so they are stuck near a volcano, unable to move. (example Mexico)

Question 26

For a volcano eruption you have studied, give a brief overview on the location and what is happening

Answer 26

Case study - Soufriere hills erruption, montserate

Location - Montserrat (British territory), found in the Caribbeans (North America). Country is a ledc.

Found on the boarders of the Caribbean plate (Oceanic) and North American plate (Oceanic and continental). The Caribbean plate will go under the N.A plate resulting in a subduction zone, which can cause powerful earthquakes and volcanos. in 1997 in Soufriere hills there was a very violent volcanic erruption

Question 27

For a volcano eruption you have studied, outline the short-term impacts of the eruption

Answer 27

• Approximately 20 deaths + 100 injuries
• lots of infrastructure damaged
• ports shut down
• High pressure in medical services
• sewer and filtration systems affected, sometimes can lead to diseases

Question 28

For a volcano eruption you have studied, outline the long-term impacts of the eruption

Answer 28

• Lots of time and money spent on repairing
• Extreme case of immigration, country lost more than 50% of their population in 4 years
• environmental damage
• Inflation within country

Question 29

For a volcano eruption you have studied, outline the short-term responses of the eruption

Answer 29

• U.K assisted relief & recovery
• ships were sent in to evacuate 4000 people
• an additional 5000 people were evacuated to the safe zone (away from the volcano)

Question 30

For a volcano eruption you have studied, outline the long-term responses of the eruption

Answer 30

• U.K gave 75M pounds for development
• Increase in number of hospitals
• more roads and airports built
• Exclusion zone set up near volcano