Tectonics

plate tectonics

100

Describe how convectional currents are formed 

1. Heat from the earth’s core causes the mantle material to become less dense 
2. Mantle material rises towards the surface 
3. The rising mantle material then spreads beneath the plates and drags them apart, causing divergent plate movement 
4. The mantle material then loses heat and sinks towards the core
5. Convergent plate movement occurs where the convection currents collide 
6. The materials get heated up again, and the process repeats. The rising and sinking of the mantle material forms convection currents 

300

Describe magnetic striping and explain how it supports plate tectonic theory

Magnetic striping is the zebra like pattern  symmetrical on either side of mid-ocean ridges.

Provides evidence that plates move, supporting plate tectonics theory as: 

• Oceanic plates move away from each other 
• Iron rich lava erupts from the centre of the ridge 
• Lava cools, solidifies and forms new oceanic crust 
• The crust is then pushed in both directions away from the ridge when new lava erupts and solidifies 
• When earth’s polarity reverses, the rocks record the reversals

400

Compare the similarities/differences in the formation of land forms at oceanic-oceanic divergent plate boundaries  and at continental-continental divergent plate boundaries

1. plate movement 

•  O-O two plates move apart. Decrease in overlying pressure causes parts of the underlying mantle to melt, forming magma 
• C-C two continental plates move apart. Rock between these faults collapses to form a deep rift valley with steep sides 

2. Formation of rift valleys 

• O-O magma rises through weak areas in the crust and fills in gaps caused by the spreading plates. Lava cools and solidifies to form a mid-ocean ridge. At the centre of this ridge is a rift valley  
• C-C  rock between these faults collapses to form a deep rift valley with steep sides 

3. Formation of volcanoes 

• O-O Magma rises and cooks to form submarine volcanoes, which may break the surface to form volcanic islands 
• C-C rock fractures and forms parallel faults. The decrease in overlying pressure causes parts of the underlying mantle to melt, forming magma. Magma rises through cracks to form volcanoes 

500

Describe seafloor spreading and how it supports plate tectonic theory. include sediment accumulation, evidence of sediment formation etc 

Seafloor spreading causes new layers of rocks and land to form near fault lines. These show evidence of sediments being moved and older sediments moving further away from the fault lines and newer land formed closer to fault lines. This shows that tectonic plates are moving to form those fault lines and are causes for the rocks to move.

earthquakes

100

Describe where earthquakes are generally found.

• they occur along plate boundaries 
• largest concentration of earthquakes is at the Pacific Ring of Fire 
• commonly located along convergent plate boundaries at subduction zones 

200

Describe the process of an earthquake.

1. rock masses on either side of a fault are pushed by tectonic forces
2. friction causes them to get locked and stress build up 
3. when stress exceeds the strength of the fault, the rocks snap or suddenly move into a new position 
4. this sudden movement causes seismic waves to be released, which results in ground shaking

300

Describe and explain the impacts of tsunamis by earthquake

1. destroy ecosystems

• seawater can flood huge areas of coastal wetlands and forests damage habitats
• Large amounts of debris carried in by the waves can pollute these areas, damaging ecosystems and killing wildlife 

2. Destroy properties and infrastructure 

• Fast moving water + debris can sweep away infrastructure 

3. Disrupts services 

• Fast moving water + debris can snap electricity and communication cables
• Can also sweep away roads and railways —> difficult to rescue people 

4. Can kill people 

400

provide a real life example for ground shaking, and explain how it affects natural and human systems

2010 Haiti Earthquake 

• Surrounding areas around factories were polluted  —> affects ecosystems, killing wildlife 
• More than 250,000 houses collapsed —> loss of lives and injury, disrupting medical services 
• About 220,000 people were killed

500

”Tsunamis cause more significant damage than soil liquefaction.” How far do you agree? Focus on the conclusion and evaluate based on scale.

In terms of scale, soil liquefaction often only occurs at places with loose soil, while tsunamis can travel over a large area and flood huge areas of coastal wetlands  and forests, and affect places far away from the origin.

volcanoes

100

Describe where volcanoes are generally located.

• generally located near convergent and divergent plate boundaries 
• not found near transform plate boundaries and continental-continential plate boundaries
• near the pacific ring of fire 

200

Give one reason why some volcanoes are more explosive than others.

• high silica magma is more vicious. as the magma rises towards the earth surface, the dissolved gases in the magma cannot escape easily. this causes more pressure build up until gases escape explosively hence resulting in violent and explosive eruptions
• low silica magma is less vicious magma. as magma rises towards the earths surface, the dissolved gases in the magma can escape easily. less pressure build up which results in a gentle and more effusive eruptions

300

Describe and explain the impacts of Lahars caused by volcanic eruptions

1. Destroy ecosystems 

• Can cover forests and other ecosystems with thick mud which hardens, destroying ecosystems 

2. Destroy properties and infrastructure 

• Can bury houses and buildings, destroying them 
• Can cover farms with hardened mud

3. Blocks railways and roads 

• Makes it harder to supply emergency aid 

4. Threatens public health 

• Can bury houses and its residents, resulting in loss of lives 

400

Provide an example for Pyroclastic flows and explain how it affects natural and human systems.

2010 Merapi eruption in Indonesia.

• About 350 people were killed —> loss of lives 
• Huge area of forest were burned —> biodiversity loss 
• Hot flows burn through homes, properties and infrastructure —> disrupts services and displaces people 

500

”People should not live near volcanoes due to the hazards associated with it.” To what extent do you agree? Focus on the conclusion.

In terms of time, most benefits provided by volcanoes take a period of time to be implemented, such as fertile soils. Benefits like extracting mineral and fossil fuels also occur over a period of time and are conditional. On the other hand, volcanic hazards occur also immediately, and can cause significant harms in a short period of time.

disaster risk management

100

Define disaster risk management for tectonic hazards.

Disaster risk management refers to the potential damage to properties, injuries and loss of lives from a disaster in a given period of time. It is determined as product of the interaction between tectonic hazard, vulnerability and exposure to earthquake and volcanic eruptions 

200

How do economic challenges for a developing country hinder development? Provide 1 challenge.

• When countries have to channel money to rebuilding after a tectonic hazard, their development may be slowed down as less money can be invested in other areas such as infrastructure and education
• Detrimental in developing countries where the need for development is highest and where funds are lacking 
• Poverty reduction progress may be affected as people are driven into poverty and their standards of living drop when they lose their source of income and homes 

300

How do soil and rock properties affect disasters?

• As seismic waves travel from hard rocks to soft soil, the waves get amplified 
• 
  
  • Waves slow down but get bigger 
  • Soft, loose soil will shake more intensely than hard rock, increasing the likelihood of buildings and bridges collapsing 
  • People will more likely be trapped in buildings —> loss of lives 
  • Solid rock is more compact and will shake less intensely 

400

How is restoring and improving facilities and living conditions of affected communities effective in managing disasters?

• Constructing hazard resistant buildings and infrastructure 
• Retrofitting surviving buildings and infrastructure with hazard resistant features 
• Allowing residents to eventually return to their original homes, keeping communities intact after a disaster 
• Providing housing assistance, which are hazard resistant and are of better quality, to those who lost their homes or were displaced 

These strategies enable the affected communities to rebuild their lives after the disaster, as well as minimising their vulnerability and exposure to tectonic hazards 

500

Which challenge, engaging relevant stakeholders to collaborate management strategies into their practices or extent of community’s resources harder to manage? Justify why.

Engaging relevant stakeholders to collaborate management strategies requires the government to take charge and requires a lot of time as stakeholders need to trust and work with the government well in order to collaborate with them. It may also require extensive resources to form agreements and contracts if international, and high amounts of manpower if within a country. However, extent of community’s resources requires lesser time as resources can be deployed immediately.

Mystery

100

How do scientists study magnetic striping?

Oceanic crust is made of basalt with iron rich materials 

Minerals align themselves with the orientation of the earth’s magnetic field, recording the earth’s magnetic polarity

300

Describe the environmental consequences of volcanic eruptions

• Volcanic eruptions may cause landslides that bury large areas of forests, resulting in the loss of biodiversity. 
• Volcanic eruptions may release debris that may fall into floods that may disrupt aquatic ecosystems. 

400

Name a place where many people live near volcanoes for their benefits

Bali indonesia is a place that is known for its paddy fields near volcanoes due to the fertile soil.

500

‘Some strategies for disaster response management to the threat of tectonic hazards are more effective than others.’ To what extent do you agree with this statement. Focus on the conclusion :)

The extent of effectiveness is limited by place. In areas with high resources, search and rescue efforts are easier and people can evacuate timely as well. In areas suffering from economic problems, resources may not be devoted to disaster management.