Physical - Hazards

Question 1

Concept of a hazard:
What is it?

Answer 1

A hazard is something that is a potential threat to human life or property.

Natural hazards are naturally occurring events that have the potential to cause damage or harm to people and the environment.
Geophysical hazards: caused by land processes like earthquakes, volcanoes, landslides, tsunamis.
Atmospheric: caused by climatic processes like cyclones, storms, droughts, wildfires
Hydrological: caused by water movement like floods and avalanches.

Question 2

Concept of a hazard:
Key terms:

Answer 2

1. Disaster: the impacts of the hazard, when the interaction between humans and a natural process has a significant effect on society, property or human life. (Can be man-made also).
   Degg’s model.
2. Risk: the likelihood that humans will be seriously affected by the hazard
3. Vulnerability: how susceptible a population is to the potential impacts of the hazard.

Question 3

Concept of a hazard:
Characteristic human responses:

Answer 3

Human attitudes:
- Fatalism: A defeatist attitude of acceptance that hazards are natural and we cannot control them. Interference could be detrimental. Nature must be able to take its course and losses must be accepted. (Can also be due to religious acceptance - acts of God attitudes).

• Domination: As technology increases, the methods of predicting hazards become more advanced. This can help us predict and dominate the effects of natural hazards and overcome them, stopping deaths from occurring. (e.g., using EWS, remote sensing, seismic monitoring, communication advances).
• Adaptation: Once we accept that natural events are inevitable, we can adapt our behaviours so that losses can be kept to a minimum. (e.g., harnessing geothermal energy from a volcano).

Question 4

Concept of a hazard:
Characteristic human responses:

Answer 4

1. Prevention: people can try and prevent a hazard or reduce its magnitude. This is impossible for somme hazards like volcanoes, but can be done for others (like for floods you can build flood defences).
2. Risk sharing: a form of ​community preparedness​, whereby the community ​shares the risk posed by a natural hazard and ​invests collectively​ to mitigate the impacts of ​future hazards​. They also share the benefits or costs of their efforts. E.g. the community collectively funding insurance for the area.
3. Mitigation: People mitigate the impacts of hazards. This can be through prediction (working out where and when the hazard will occur), allowing people to respond efficiently (evacuating, or warning people).
4. Adaptation: It can also be through adapting to hazardous environments, like through building earthquake proof buildings, or terrace farming (near volcanoes) or building dams to ensure a water supply.
5. Prediction: using EWS, remote sensing, observatories, etc to predict when and where the hazard will occur and to warn the public. Govs can co-ordinate to best predict hazards and then manage them from there.

Question 5

Concept of a hazard:
Characteristic human responses:

Answer 5

The success of managing hazards depends on:

• Hazard incidence (frequency of hazards)
• Magnitude/intensity (how powerful it is)
• Distribution (the areal extent of the hazard).
• Level of development (wealth/technology availability in the country).

Generally, hazards with low incidence and high magnitude are the most destructive and hardest to predict, manage and adapt to. They harm the least developed countries the most.

Question 6

Concept of a hazard:
Economic vulnerability to hazards:

Answer 6

Economic vulnerability:

• Poverty means less stable living conditions, less resources for safety and response, less likely to have insurance to help, less access to medical help, less stable employment.
• Also, the poor are more likely to live in hazardous areas.
• The poverty of the governments means less programs of prevention or prediction or mitigation of hazards, less spent on education of the dangers, and less help from the state.
• Also, the country’s technology availability will determine the extent of the impacts (Japan’s earthquake proof buildings, prediction measures). Poorer places have less coping or adapting capacity (Philippines vs Japan).

Question 7

Concept of a hazard:
Social vulnerability to hazards:

Answer 7

Social vulnerability:

• Age: children and the elderly are more likely to be harmed as they have less physical capacity to survive. They will have less of their own money, children will lack education, etc.
• People with disabilities are very vulnerable, some emergency response technologies cannot accommodate them.
• Social norms: means that uneducated girls (where this is common) will be less prepared. Ethnic groups can be excluded from society and forced to live in a hazardous area (South Africa is very segregated, used to be based on race, now based on income, but very linked. The black communities are forced into marginal land that is more prone to hazards). (This also happens in Brazil to an extent with favelas).

Question 8

Concept of a hazard:
Educational vulnerability to hazards:

Answer 8

Educational:

• We learn how to avoid or reduce impacts through education. Illiterate communities are harder to save as they can’t read warnings.
• When the community includes professionals or knowledgeable people, they can help the rest.

Question 9

Concept of a hazard:
Environmental vulnerability to hazards:

Answer 9

Environmental:
- Rock type in an earthquake (can cause liquidation), shape of coastline or availability of high ground in a tsunami, cliffs that can have rock fall or land slides, etc. These can cause extra secondary impacts to the hazard.

Question 10

Concept of a hazard:
Modifying vulnerability to hazards:

Answer 10

• Governments can actively try to reduce inequality and start programs to help vulnerable people financially (even with aid money).
• New tech can be used to predict hazards and prevent damage (although costly and doesn’t save property).
• Setting up exclusion zones and hazard mapping (mitigation).
• Prevention through strict building laws (Japan earthquake proof buildings).
• They can try move vulnerable people away – this would save lives and property, but high population densities in hazardous areas prevents this and goes against some people’s traditional lands.
• Educational preparedness days, school programs, earthquake drills, earthquake kits from NGOs with essentials (low cost).

Question 11

Plate tectonics:
Convergent/Destructive (subduction) plate boundaries:

Answer 11

Destructive (subduction):

• Two plates move towards each other, the denser oceanic plate subducts under the less dense continental crust.
• This creates an ocean trench and a subduction zone. In this subduction zone, friction from the contact of the two plates can cause earthquakes (when they lock and release), and heat.
• The subducting oceanic crust melts to produce magma as it gets closer to the mantle (where it is hotter). This expands, becomes less dense due to the heat, and rises through weaknesses in the continental crust, erupting on the surface as a volcano.
• Where the oceanic crust subducts, ocean sediment is scraped off the seabed and onto the continental plate, forming fold mountains, causing severe earthquakes, composite explosive volcanoes, ocean trenches and fold mountains.

Question 12

Plate tectonics:
Convergent/Destructive (Collision) plate boundaries:

Answer 12

• Two continental plates of the same density move towards each other. No subduction takes place as they are similar densities, and instead the sediment and rocks at the plate margins crumple and fold on collision.
• This creates mountainous ridges (Himalayas).
• These cause fold mountains and some severe earthquakes.
• Over time, these ridges may be weathered, and eroded by the effects of glaciers or rain.

Question 13

Plate tectonics:
Divergent/Constructive plate boundaries:

Answer 13

• Two oceanic plates pull apart (diverge). The rising magma plume forces the ends of the plate to push up and buckle.
• Magma is pushed through the gap between the plates, and cools to form new, solidified basalt rock.
• This mostly forms submarine shield volcanoes underwater.
• With successive eruptions over millions of years, they can grow until they reach the surface and become a volcanic island (Iceland).
• They cause gentle earthquakes and shield volcanoes, rift valleys (East African Rift Valley), and ocean ridges (Mid-Atlantic).

Question 14

Plate tectonics:
Conservative plate boundaries:

Answer 14

• Two plates move in opposite/the same directions (at diff speeds). There is no subduction or creation of new rock.
• Movement is not smooth, and friction is generated between the two plates. This causes the plates to lock together so there is an increase in potential energy.
• At some point, pressure overcomes friction and the plates are suddenly released, jolting past each other.
• This sudden release of energy causes earthquakes (some severe).
• This also creates upland ridges (like the San Andreas Fault).

Question 15

Plate tectonics:
Hotspots:

Answer 15

• Magma plumes are created through radioactive activity under the crust.
• Then when a weakness in the plate boundary above, moves over the plume, magma is released and solidifies to make a volcano on the surface.
• This can be an island chain like Hawaii. As the plate moves, new weaknesses are above the plume, creating a chain of volcanic islands that get older and dormant as they move away from the plume.
• Also, hotspots can be over mid-ocean ridges as hot rock is forced out and forms islands (Iceland), or on land (East African Ridge, as the Arabian and Somalian plates pull apart, plumes are forced out).

Question 16

Plate tectonics:
Characteristic processes: Seismicity and vulcanicity:

Answer 16

1. Destructive (subduction): The most hazardous
   These cause severe earthquakes and composite volcanoes, ocean trenches and fold mountains. (High seismicity and high vulcanicity).
2. Destructive (collision):
   These cause mountain ridges and fold mountains, and some severe earthquakes, but no volcanoes. (Mid-high seismicity and low vulcanicity).
3. Constructive:
   These cause gentle earthquakes and shield volcanoes (weaker), rift valleys and ocean ridges. (Mid-low seismicity and high vulcanicity, although they are weaker).
4. Conservative:
   These create earthquakes of varying severities and upland ridges, but no volcanoes. (High seismicity and low vulcanicity).

Question 17

Plate tectonics:
Explaining the distributions of volcanic and seismic activity globally:

Answer 17

• There is clearly an unequal distribution.
• They are mainly in clusters (like in Asia or the Americas).
• They also appear in linear groups, this is due to them mainly being on plate boundaries.
• For example, along the Mid-Atlantic Ridge, the Southwest and Southeast Indian ridges, and on the ring of fire (Eastern Asia and Western Americas).
• 75% of the world’s volcanoes are there (450) and 90% of the earthquakes.
• This is a collection of convergent plate boundaries with subduction zones, showing these formations have the most seismicity and vulcanicity.
• They also occur at constructive plate margins (Iceland) and hotspots (Hawaii), to make it even more unequal.
• They don’t occur on constructive plate margins.
• Further, the deepest earthquakes also form on the ring of fire due to this concentration of divergent plate boundaries.
• Therefore, it is a very unequal distribution, with most being situated along the ring of fire and convergent plate margins.

Question 18

Volcanic Hazards:
What is a volcano?:

Answer 18

Definition: A volcano is a vent in the Earth’s crust through which lava, tephra (ash, dust and rock) and gases erupt.
Molten rock beneath the surface is called magma, but above is lava. Magma is stored in magma chambers. Fissures and fractures in the crust create areas of low pressure that allow some of the rocks to become molten and rise. If they reach the surface, they are intrusive.

Question 19

Volcanic Hazards
Features of a volcano:

Answer 19

1. Magma Chamber: store of hot molten rock beneath the volcano.
2. Main vent: The tunnel in which the magma rise to the top of the volcano.
3. Crater: Opening at the top of a volcano
4. Lava flow: Lava escaping from the crater and flowing down the sides
5. Volcanic cloud: Gas, steam and ash escaping from the volcano.
6. Tephra: Large pieces of rock ejected from the volcano.
7. Ash and Lava: built up and solidified over time to form the sides of the volcano.
8. Secondary vent: Smaller vents in the sides, allowing magma to escape from the side of the volcano.

Question 20

Volcanic Hazards
Relations to plate tectonics: spatial distribution:

Answer 20

Most volcanic eruptions happen on constructive and destructive boundaries:

1. Constructive plate boundaries:
   - Basaltic lava is formed here in shield volcanoes - it is very hot and has a low viscosity (runny), so it flows easily and quickly. Eruptions of shield volcanoes are frequent and last a long time, but they are not violent.
   - If the margin is underwater, magma rises to fill the space left by plates moving apart, forming ocean ridges.
   - If the margin is on land, as plates pull apart, forming rift valleys, they become thinner and magma is able to break through at the surface (East African Rift Valley).
2. Destructive plate boundaries:
   - Acidic silica rich lava is formed here, which is cooler and more viscous (thick), and flows less easily of quickly. The eruptions are short lived and infrequent

Question 21

Volcanic Hazards
Types of hazards:

Answer 21

1. Pyroclasts: Hot fragments of rock ejected at high speeds, can cause damage and deaths (lapilli, lava bombs, ash clouds).
   Tephra is a collective term for all pyroclasts at once (ash cloud and flying rocks).
2. Eruption columns: The gases in the silica rich and gaseous magma decompress to form up-thrusting gases and tephra. They include white cloud columns of steam, pyroclastic material and ash. These can form PYROCLASTIC FLOWS (nuées ardentes), which are fatal. This is caused when the eruption column collapses and hot, gas charged with high velocity flows of tephra and ash are produced, flowing fast down the side of the volcano. This covers people and suffocates them. They can move up to 150mph and be over 800 degrees hot.
   Lower density ones are called pyroclastic surges that destroy everything in their path.
   EX: 1980 Mount St. Helens caused by pyroclastic surges and lateral blasts, destroying a 20km radius area.

Question 22

Volcanic Hazards
Types of hazards:

Answer 22

3. Poisonous gases: Ash filled gases (inc Carbon monoxide, hydrochloric acid, CO2 and sulphur dioxide) can contaminate acid rain and cause disease and starvation from crops dying. Water sources can be contaminated and livestock/people can die. They also damage the ozone layer.
   EX: Sulphur dioxide was ejected at Mount Pinatubo in 1991 (Philippines).
   And in 1970 at Lake Monoun in Cameroon, 1,700 people suffocated overnight due to a release of CO2 in an underwater eruption.
4. Lateral Blasts: Rapid decompressions of dissolved gases due to the exposure of masses of magma by a landslide. It causes a sudden, sideways release of pulverised rock and hot gas. They travel at the speed of sound and are lethal in the blast zone.
   EX: Mount St Helens 1980 had lateral blasts up to 600km away.
5. Atmospheric effects: Eruption columns can travel into the atmosphere and ash into the winds. This leads to dangerous air and odd optical effects. It reduces vision and causes respiratory issues, as well as adding to the EGE. Ash fall covers areas in thick ash.
   EX: Mount St Helens 1980 had ash fall over 20,000miles away.
   And the 2010 Iceland eruption stopped air travel in Europe.

Question 23

Volcanic Hazards
Types of hazards:

Answer 23

3. Poisonous gases: Ash filled gases (inc Carbon monoxide, hydrochloric acid, CO2 and sulphur dioxide) can contaminate acid rain and cause disease and starvation from crops dying. Water sources can be contaminated and livestock/people can die. They also damage the ozone layer.
   EX: Sulphur dioxide was ejected at Mount Pinatubo in 1991 (Philippines).
   And in 1970 at Lake Monoun in Cameroon, 1,700 people suffocated overnight due to a release of CO2 in an underwater eruption.
4. Lateral Blasts: Rapid decompressions of dissolved gases due to the exposure of masses of magma by a landslide. It causes a sudden, sideways release of pulverised rock and hot gas. They travel at the speed of sound and are lethal in the blast zone.
   EX: Mount St Helens 1980 had lateral blasts up to 600km away.
5. Atmospheric effects: Eruption columns can travel into the atmosphere and ash into the winds. This leads to dangerous air and odd optical effects. It reduces vision and causes respiratory issues, as well as adding to the EGE. Ash fall covers areas in thick ash. This can also cause acid rain, that kills crops, contaminates water supplies, etc.
   EX: Mount St Helens 1980 had ash fall over 20,000miles away.
   And the 2010 Iceland eruption stopped air travel in Europe.

Question 24

Volcanic Hazards
Types of hazards:

Answer 24

6. Lava flows: Magma flows onto the crust in the form of lava. Flow rate is dependent on the eruption. As lava cools, viscosity increases and speed reduces. It can travel miles and damage property and set fires and be fatal. The more acidic lava is at convergent plate margins and is more dangerous than basaltic lava at divergent margins.
   EX: Kilauea in Hawaii since 1983 has erupted basaltic lava flows that have destroyed more than 200 homes.

Question 25

Volcanic Hazards
Types of secondary hazards:

Answer 25

1. Landslides: The dislocation of land and rocks by magmatic pressures, cause huge flows of rock, mud and tephra, causing destruction of property and lives.
   EX: The largest landslide was in 1980 at Mt. St. Helens.
2. Lahars: As rain or meltwater flows loosen tephra, volcanic mudflows move downhill quickly (50mph), as determined by topography. This causes extensive destruction to property and lives.
   EX: Happened in Mt. Pinatubo 1991.
3. Flooding: Caused by submarine eruptions displacing water and rock. The blockage of rivers by lahars, or lava flows, this causes floods of fresh water which can be fast flowing. Causes dramatic changes in erosion and decomposition of patterns of rivers. Also can be caused by the meltwater or glacial melt from the peak. Destruction of property and lives can be caused.

Question 26

Volcanic Hazards
Magnitude and Frequency of volcanic hazards vary:

Answer 26

1. Magnitude: Volcanic events range from small, slow lava flows to huge eruptions of lava and tephra.
   Magnitude can be measured with the VEI scale (Volcano Explosivity Index), which grades volcanoes on how much material was erupted and how high it was blasted from 0 to 8.
2. Frequency: Volcano frequency is almost impossible to predict. Less frequent volcanoes means a larger magnitude. (some take millions of years, others a decade).
3. Randomness v regularity: some volcanoes erupt in regular intervals, whereas others are dormant for millions of years and then erupt many times quickly.

Question 27

Volcanic Hazards
How to predict and monitor volcanoes:

Answer 27

4. Predictability: The regularity with which a volcano erupts can help scientists to predict when it might erupt again.
   They do this by:
   - Seismometers: measures earthquakes, the rising magma causes earthquakes as it cracks and fractures rocks.
   - Ground deformation: They use tiltometers and laser beams to measure changes in the shape of the volcano as indicated by changes in the slope of the ground and distances between fixed objects. The rising magma causes the sides of the volcano to inflate.
   - Geophysical measurements: They measure the changes in rock magnetism. Magma is dense and rich in iron, which effects magnetism.
   Hydrology: Gases released may be absorbed in water and these can be measured. These gases are released when magma rises (Sulphur dioxide, CO2).
   - Gas: They measure concentrations of sulphur or chlorine in the air as magma rises.
   - Remote sensing: Cameras in the volcano crater or in space, can record small eruptions or sense temp changes, or record the lava level in the lava lake. These minor eruptions and changes and increases in temp suggest rising magma.

Question 28

Volcanic Hazards:
Primary and secondary impacts:

Answer 28

Primary: direct results of the eruption. (P)
Secondary: results of the primary impacts. (S)

1. Economic impacts:
   - Eruptions destroy businesses, and ash clouds prevent air travel and damage crops. (P)
   - Damage to buildings and infrastructure can be expensive to repair. (P)
   - Eruptions can deter or destroy tourism industries and attractions. (S)
2. Social impacts:
   - People are killed and infrastructure destroyed by various hazards. (P)
   - Pyroclastic flows and lava flows start fires that damage buildings (P).
   - Mudflows and flooding from ice meltwater can cause further damage/death (S).
3. Environmental:
   - Ecosystems are damaged or destroyed by hazards. (P)
   - Acid rain can cause acidification of marine ecosystems and damage crops, trees and soils (P).
   - Volcanic gases contribute to the EGE and global warming (S)
   - Clouds of ash and debris can reduce the amount of sunlight reaching earth, decreasing temps (Iceland eruption 2010) (S).
4. Political:
   - Damages to agricultural land can cause food shortages, leading to conflict and political unrest (S).
   - Govs may have to spend money on repairing damages rather than development initiatives (S).

Question 29

Volcanic Hazards
Risk management: Preparedness:

Answer 29

Preparedness: To be ready and able to deal with the volcano
This is what happens before the eruption to minimise risk and vulnerability.
- Authorities can install monitoring systems (EWS) and good communication systems to predict eruptions and make plans for evacuating the people.
- If an eruption is immanent, authorities can stop people going into high-risk zones (exclusion zoning).
- Authorities need to set aside funds to have in case of the eruption.
- Individuals can make sure they are prepared (finding their nearest emergency shelters and making an emergency kit).
- Communities can set up search and rescue teams or fire response units to tackle impacts.

Question 30

Volcanic Hazards
Risk management: Prevention:

Answer 30

Prevention: To stop something from happening

• It is not possible to prevent a volcano, as their frequency is hard to measure and their magnitude varies.
• However, sometimes it is possible to prevent eruptions posing a risk to people. For example, authorities not allowing people or developments in high risk areas.
• We can also divert lava flows by creating controlled explosions to have it move away from towns/people.

Question 31

Volcanic Hazards
Risk management: Mitigation:

Answer 31

Mitigation: To reduce the severity of volcanic impacts.
Short term:
- International aid used to fund humanitarian programs.
- Provisions of emergency services.
- Evacuating the population at risk.
- Providing emergency temporary supplies (food, shelter, water and services like schools, hospitals, etc).
Long term:
- Rebuilding infrastructure.
- Implementing control structures to reduce the effects of flooding.
- Land zoning and exclusion zones
- Building reinforcements to avoid further damage.

Question 32

Volcanic Hazards
Risk management: Adaptation:

Answer 32

Adaptation: To change one’s behaviour to live with the volcano and the associated hazards, maximising the benefits and minimising the risks.

• Redevelopment of infrastructure to be more suitable to volcanic areas (Japan earthquake proof buildings).
• Capitalising on opportunities: farming (volcanic soils are very fertile) or developing tourism around it.
• Harnessing the geothermal heat (Iceland)
• Testing ESW and other monitoring systems regularly.

Question 33

Volcanic Hazards
Case Study: Montserrat 1997: Impacts:

Answer 33

Montserrat is above a destructive plate boundary (North American and Caribbean plates), so the volcano is a composite one (violent, acidic lava).

• Primary effects: Just in the largest eruption of many, 4-5 million m cubed of material was released in 20 mins.
• Pyroclastic flows and tephra covered the area of miles.

1. Economic impacts:
   - The total loss in value to homes and investments was $1billion.
   - Over 20 villages and 2/3 of homes on the island were destroyed by pyroclastic flows.
   - Tourists were deterred and businesses were destroyed, disrupting the economy (tourism now increasing though).
   - Schools, hospitals, the airport and the port were destroyed.
2. Social:
   - 19 people dies and 7 injured.
   - Hundreds lost their homes.
   - Fires destroyed many buildings (local gov offices, police stations, petrol stations).
   - The population has declined - 8,000 of the 12,000 inhabitants left after the eruption and many haven’t returned.
3. Environmental:
   - Large areas were covered in volcanic material (the capital buried under 12m of mud and ash).
   - Vegetation and farmland was destroyed.
   - Volcanic ash from the eruption has improved soil fertility.

Question 34

Volcanic Hazards
Case Study: Montserrat 1997: Responses:

Answer 34

Responses:
Short term:
- NGOs (Red Cross) set up temporary schools and hospitals and gave medical support and food/water (mitigation).
- £17million of UK aid paid for temporary buildings and water purification systems (mitigation/adaptation).
- Troops from the US and UK Navies came to help the evacuation process (mitigation).
- Exclusion zones were defined in the south and visits were restricted (mitigation/adaptation).

Long term:

• The Montserrat volcano observatory was set up in 1995 and predicted the eruption in 1997 (preparation).
• EWS were set up to warn people via sirens, the media and speakers (prevention).
• They rebuilt the tourism industry around the volcano and exploited the geothermal energy and sold volcanic sands (adaptation).
• Vegetation is regrowing as the ash, lava and lahar deposits break down, the soils are fertile and used for cash crops (adaptation).
• 2/3 of the island is an exclusion zone and EWS and sirens are tested daily (mitigation)
• UK aid has reached $420million since 1995 (preparation)
• A three year development plan for houses, schools, hospitals, infrastructure and agriculture has been funded by the UK (adaptation).
• By 2005, many people moved back but the capital stayed in an exclusion zone (mitigation/preparation).
• In 1998, the Montserrat citizens were granted full legal residency rights and citizenship in the UK from 2002. This resulted in a top-heavy population as many young people left for the UK (adaptation/mitigation).

Question 35

Seismic Hazards:
The nature of seismicity and its relation to plate tectonics:

Answer 35

• *Seismic hazards occur near plate margins:**
• Most occur on destructive (subduction) margins, and conservative margins. (Some do also occur on constructives).
• The nature of an earthquake and its magnitude is determined by:
  1. Margin type: The biggest EQs occur at subduction zones or conservative boundaries, due to the huge pressure they create (and melting at subduction zones). EQs at constructive boundaries tend to be lower in magnitude.
  2. Rate of movement: Tectonic plates move in relation to each other at different rates. There is no clear relationship between rate of movement and EQ magnitude.
  3. Depth of focus: An EQ’s deep focus tends to be higher in magnitude than shallow focuses. However, deep focuses do less damage, as their shock waves need to travel further, reducing their power through natural energy loss.
• *Lower magnitude hazards occur frequently:**
  1. Magnitude and frequency: hundreds of low magnitude EQs happen every day, but higher magnitude EQs are less frequent.
  2. Randomness and regularity: EQs and other hazards wont seem to follow any clear pattern or trend, and their occurrence is random.
  3. Predictability: scientists can monitor the movement of tectonic plates (using lasers) to predict the areas at high risk, using seismometers (detecting increased vibrations leading to an EQ), or using radon gas detectors (which is released from cracks in the crust - an increase suggests an EQ). However, it is not possible to tell when the EQ will happen, and what magnitude it will be.

Question 36

Seismic Hazards:
What are Earthquakes, and how are the caused?

Answer 36

• *Earthquake def:**
• A sudden release of energy or pressure from the Earth’s crust that produces seismic shock waves. (They are the primary hazard associated with seismicity).
• Earthquakes/Shockwaves:
  
  • They are caused by tension that builds up at all types of plate margin, creating potential energy.
  • When the plates jerk past each other, it sends out shockwaves (vibrations) as kinetic energy, that become the shockwave.
  • These spread out from the focus (so the waves are stronger nearer the focus).
  • The epicentre is the point on the surface where the EQ is first felt. it is directly above the focus.
  • EQs cause ground shaking, and sometimes ruptures (splits) along the fault line.
• Types of fault lines:
• Thrust fault: When one block of crust is forced on top of another. These are found in collision zones (mountain ranges, like the Himalayas).
• Normal fault: This is when two blocks pull apart, stretching the crust into a valley. EX: The East African Rift Valley.
• Strike-Slip fault: When 2 plates move past each other and then stop moving, due to the friction. Eventually, the pressure will build up enough and the plates will slip, releasing the energy and causing the EQ. EX: The San Andreas Fault line.

Question 37

Seismic Hazards:

How EQs are measured:

Answer 37

• The Richter scale (quantitative):
  
  • This measures the magnitude of an EQ, it has no limit, and is logarithmic (goes up In x10). So a mag 4 EQ is 10x less magnitude than a mag 5. Major EQs are 7+.
  • Magnitudes 1-5 are not felt by humans (very frequent). Above 6 is felt.
• The Moment Magnitude Scale (MMS) (quantitative):
  
  • This is based on the total amount of energy released by an EQ. It is also logarithmic and has no upper limit. It is more accurate than the Richter scale and so is more widely used.
• The Mercalli scale (qualitative):
  
  • This measures the impacts of an EQ using observations of the event and its damage (reports/photos). The scale is between 1-12, with 12 being a totally destructive EQ.
  • It can be used to measure older historical events that were not officially/accurately recorded (using cave drawings/art/literature, etc).
  • However, it is less used as it is less reliable and more subjective (events can be exaggerated).

Categorisation of EQs:

• Great or total damage, many deaths and injuries (Mercalli scale 7-12).
• Physical Impacts: high magnitude on Richter scale, shallow focus, sans and clays vibrate more
• Human Impacts: high population density, residential area, self-built housing, lack of emergency procedures.
• Superficial damage to buildings, few casualties (Mercalli scale 1-6).
• Physical Impacts: Low magnitude, deep focus, hard rock surface.
• Human Impacts: Low population density, urban area with open spaces, EQ proof buildings, regular EQ drills.

Question 38

Seismic Hazards:

Other hazards created by earthquakes:

Answer 38

• Tsunamis:
  
  • These are large waves caused by the displacement of large volumes of water.
  • They are triggered by underwater EQs. These cause the seabed to move, which displaces water. Waves radiate out from the epicentre of the EQ. The greater the movement of the sea floor, the greater the volume of water displaced, and the bigger the wave.
  • A tsunami will usually be more powerful if it starts close to the coast, as the waves loose energy when travelling.
  • They waves travel very fast in deep water so they can hit the shore without much warning. This means they can result in a lot of death and destruction.
  • EX: Indian Ocean Tsunami 2004 - magnitude 9.1 EQ due to a rupture of the Sunda Megathrust fault, cased a 30m high wave.
  • Social Impacts: This caused 228,000 deaths, due to a lack of natural mangrove defences (removed for tourism), lack of warning systems (many people were on the beaches at the time), high populations and lack of sanitation means diseases spread fast.
  • Economic impacts: Many communities were dependant on fishing, and tourism, and agriculture. Ships, beaches destroyed and water sources contaminated and salinised (stopping irrigation and making soils infertile).
  • Environmental impacts: Mangroves, coral reefs and forests destroyed by wave surges, more ecosystems polluted by chemical waste in the floodwater.
  • Responses: $14bn aid given, the US gave aircraft for search and rescue, surveying, and transport of aid cargo. Corruption hampered aid efforts though (Sri Lanka refused Israeli aid). Tsunami warning systems implemented in response.
• Landslides and Avalanches:
  
  • Ground shaking can dislodge rocks, soils, snow, causing landslides or avalanches that move downslope quickly.
  • Shaking can also loosen ground material, making it easier for water to infiltrate. The weight of the extra water may trigger a landslide even after ground shaking has stopped.
• Soil liquefaction:
  
  • When soil is saturated with water, the vibrations of an EQ can cause it to act like liquid (depending on geology).
  • This makes the soil weaker and easier to deform, so it is likely to subside, (esp when there is weight on it from buildings or cars, etc).

Question 39

Seismic Hazards:

Global distribution of earthquakes:

Answer 39

6 Mark Question:

1. There is an uneven global distribution.
2. There are clear clusterings in areas like East Asia and the Western coast of the Americas.
3. There are also clearly linear distributions, like in the Atlantic Ocean, or the Indian Ocean.
4. This is because earthquakes follow the distribution of plate boundaries.
5. For example, the clusterings around Asia and the Americas, correspond to the ring of fire (where 90% of EQs happen), as this is a ring around the Pacific of divergent subduction zone plate margins.
6. The linear distributions is due to the mid-ocean ridges of The Atlantic and Indian Oceans.
7. EX: This is why Iceland, Japan and Chile experience so many EQs.
8. Further, we can also see that the distribution of the deepest EQs is clear. It follows the distribution of the divergent plate margins, as these subduction zones are deeper, and create more potential energy for higher magnitude EQs.

Question 40

Seismic Hazards:

The Anatomy of an EQ:

Answer 40

• Transverse Waves: These waves cause side-to-side movements, which cause much damage.
• Longitudinal Waves: These cause up and down movements.
• Primary Waves: These travel the fastest and cause back-and-fourth movements.
• Secondary Waves: These are slower and cause movement from side to side.
• Surface Waves: These arrive later, as the other waves travel from the focus to the epicentre.

Question 41

Seismic Hazards:

Primary and Secondary Impacts of Earthquakes:

Answer 41

• Primary Impacts are the direct impacts of the hazard (e.g. deaths from building collapse)
• Secondary Impacts are the results of the primary impacts (e.g. electric wires causing fires, which kill people).
• Social Impacts:
  
  • EQs can cause buildings to collapse, killing and injuring people, and leaving others homeless. (P)
  • EQs and liquefaction can cause gas lines and power lines to break, starting fires that kill people. Broken water pipes cause flooding, and lack of water can make it hard to put out fires. (S)
  • Lack of clean water can cause disease to spread. (S)
  • Tsunamis can flood large areas, killing people and causing damage to property. (P)
• Economic Impacts:
  
  • EQs can destroy businesses through ground shaking and liquefaction. This damages the economy of the region. (P)
  • Damage to industry may mean that the country has to rely on expensive imports of goods/energy. (S)
  • Damage to buildings and infrastructure can be very expensive to repair + insurance payout. (P)
• Political Impacts:
  
  • Govt buildings destroyed. (P)
  • Shortages of food, water and energy can cause conflict and political unrest. (S)
  • Govts may have to borrow money to repair damages, putting the country in debt. Money that is needed for development, may need to be spent on repairs. (S)
  • There can be lawlessness in the initial chaos (looting). (S)
• Environmental Impacts:
  
  • EQs can cause fault ruptures/liquefaction that destroy the environment.
  • Industrial units, including power plants, can be damaged by EQs, and tsunamis, causing leads of chemicals or radiation that damage the environment. (S)
  • Fires started by damaged gas or electricity lines can destroy ecosystems. (S)
  • Tsunamis can flood freshwater ecosystems, killing plants and animals and Stalinising the water and soils. (P)

Question 42

Seismic Hazards:

Short-term and Long-term Responses:

Answer 42

• Short-term responses occur immediately before, during or immediately after the hazard (e.g. rescuing people or evacuations).
• Long-term responses are designed to mitigate the impacts of future hazards by managing the risks.

Long term responses:

• Preparedness:
  
  • This is about preparing the area and the people there for the future.
  • Authorities can install EQ waring systems, that detect weaker seismic waves in preparation for a stronger one. The systems send out warnings by media (TV, Radio, SMS).
  • This includes educating people on how and where to evacuate.
  • Individuals and businesses can have plans for how people should respond during an EQ (e.g. staying away from buildings, finding strong door/desk frames to shelter under when inside).
  • Authorities can develop tsunami warning systems and make sure evacuation routes are well known to the people.
  • Communities can set up search and rescue teams or fire response units to tackle the impacts of a hazard.
  • Animals respond to chemical changes in groundwater and soils, that result from small earthquakes (that we can’t feel), and they move away to other areas (e.g. Toads in Italy before the 2016 EQ moved away, Snakes before the 1975 Chinese EQ moved away).
• Prevention/prediction:
  
  • It is impossible to do this in essence.
  • However, sometimes it’s possible to prevent them posing a risk to people. (E.g. authorities can prevent land that is prone to liquefaction from being built on, or build sea walls to prevent tsunamis hitting land).
  • Liquefaction can be prevented through soil stabilisation (gravel columns in the ground).
  • Avalanches can be prevented though controlled explosions.
  • Foreshocks give a precursor to a major EQ.
  • Increased levels of radon gas in soils or groundwater means risk of EQ.
  • Groundwater levels can rise die to crustal deformation.
  • Seismic Gap Theory: The Northern Anatolian Fault (Turkey) is useful to predict where the EQ will happen, but not when. This is the theory that there are relatively equal gaps in both time, and distance between historical earthquakes, and so we can predict the next one. (EX: The last EQ in Turkey was in Izmit 1999, and they believe the next will be in Istanbul).
• Mitigation:
  
  • Search and rescue, immediate emergency aid, evacuations (short-term).
  • Demolishing older, unsafe buildings and replacing them with EQ resistant ones.
  • Tsunami wave breaks and sea walls.
• Adaptation:
  
  • People can adapt their behaviour or surroundings to minimise the risks of hazards.
  • Govts can stop developments in at-risk areas.
  • Buildings can be designed to be EQ resistant (by using strong or flexible, or building specific foundations to absorb the EQ’s energy).
  • Buildings can also be designed to reduce vulnerability to tsunamis (e.g. tall, strong buildings with raised, open foundations allow people to escape quicker).
  • People can capitalise on the opportunities, like developing tourism.
  • People in the at-risk areas having insurance (HICs), or Aid (LICs), and good availability/access to relief and emergency services.
  • Changes in lifestyle choices (moving valuable items away).

Question 43

Seismic Hazards:

New Zealand and Haiti Case Studies: Impacts

Answer 43

New Zealand (Christchurch) 2011 - (subduction zone, ring of fire, 6.3 magnitude EQ, epicentre was 5km deep and 3km away from central Christchurch with a population of 350,000).

• Impacts:
  
  • 185 deaths in total, widespread building damage and infrastructure, building failures caused 175 of the deaths. (P)
  • EX: The Canterbury TV building collapsed and killed 115 people, and was very poorly designed and shouldn’t have been issued a permit. (P)
  • The port of Lyttelton is where the city’s imports/exports come from, and was extremely damaged as it was close to the focus. (S)
  • 12% of the NZ population was affected, and 165,000 of the 200,000 homes too. (P)
  • Overall, cost was around $30bn NZ$ (10% of GDP). (S)
  • Disruption: less payment systems for cash to recover due to less ATMs/power cuts. NZ$150million was sent. (S)
  • Stabilisation: financial systems were put under significant stress, and businesses didn’t survive. (S)
  • By mid 2012, retail spending had recovered, but accommodation and services industries were still suffering as tourists stopped coming. Employment (esp women) was affected in these industries. (S)
  • People forced to move away (50,000 in total). However, in 2012 people came to the area for jobs helping the recovery. (P)
  • Less FDI in the area. (S)
  • Rockfall and liquefaction caused residential damage. (S)
  • 80% of the city lost power. (S)

Haiti 2010 (EQ 7 magnitude, focus was only 13km down and 16km away from Port-au-Prince. Caused by a slip between the North American and Caribbean plates).

• 1 in every 15 people died. (P)
• 1 in every 16,588 people affected were rescued (not good). (P)
• The Haitian govt reported an estimated 230,000 people had died, 300,000 injured and 1,000,000 made homeless. (P)
• They also estimated that 250,000 residences and 30,000 commercial buildings had collapsed or were severely damaged. (P)
• The EQ caused major damage to the capital of Port-au-Prince, Jacmel and other cities. (P)
• 30% of the buildings in the capital were damaged. (P)
• Looters fought over scarce food supplies, hijacked vehicles and raided a UN warehouse were 15,000 tonnes of food were stockpiled. (S)
• Port-au-Prince’s main prison was damaged and over 4,000 prisoners were able to escape. (S)

Question 44

Seismic Hazards:

New Zealand and Haiti Case Studies: Responses

Answer 44

Economic Responses:

Haiti:

• The UN pledged $4.5bn to Haiti in 2010, but so far, only 43% has been delivered.
• The EU gave $600mill to Haiti
• In total, the nation received $13bn in international aid.
• The UN launched an appeal for $562m, helping 3 million people for 6 months. Almost half of the appeal money would be for emergency food aid, with amounts between $20 and $50 mill for health, water and sanitation, nutrition, emergency shelter, early recovery and agriculture.

NZ:

• Australia’s gov gave $5mill to the Red Cross, Japan sent search and rescue teams, China sent $1mill (as 20 Chinese people died), the EU, UK, Canada, US, UN all sent aid too.
• The Christchurch Recovery Plan was introduced, to re-build 17 major parts of the centre of the city.
• NZ$1bn of residential and non-residential building consents were granted in the following 6 months.
• People migrated into the city to find employment in the following years, to help with the recovery.

Social Reponses:

Haiti:

• The World Food Programme, set up water tanks across Haiti, with a further 12,000 bottles supplied to the capital’s main hospital. They also supplied people with high energy food.
• Immediate priorities like search and rescue, medical services and supplies, clean water and sanitation, emergency shelter, food, logistics and telecoms.
• 70 humanitarian agencies distributed emergency shelter-materials to 1.5million people.
• More than 400,000 people received non-shelter relief supplies from the Red Cross. Over 100,000 patients have been treated at either the two hospitals or four basic healthcare units set up.
• 21 emergency response units mobilised.
• The US sent an aircraft carrier to Haiti carrying marine expeditionary units to help with the search and rescue.
• A hospital ship and helicopters were also sent carrying more troops and marines, with the total number of US troops totalling around 10,000.
• Plane-loads of rescuers and relief supplies arrived from the UK, China, EU, Russia, Canada, Latin America, etc.
• The US announced it will grant leave to remain to thousands of Haitian migrants living there due to the humanitarian crisis. They can stay and work for 18 months after the crisis.

NZ:

• The city was evacuated and a state of national emergency was called.
• People migrated out of the city (50,000)
• The NZ Red Cross and government got to work quickly and implemented the Emergency Recovery Plan, they established the red zone (for no access of the centre of the city), and asked for a US Satellite to see the damage and the area from space.
• Generators were donated, emergency comms were setup (with free calls), the Army provided desalination plants, a total fire ban was implemented (due to the lack of spare water), mains water supply to homes was achieved to 70% of homes in the first week.
• Waste water and sewage systems fixed, portaloos and portable showers set up.
• Thousands helped the clean-up – 200,000 tonnes of silt needed removing from the liquefaction.

Question 45

Storm Hazards:

The nature of tropical storms and their causes:

Answer 45

They form over warm water in the tropics:

• They are huge spinning storms with strong winds and torrential rains.
• They develop over warm waters as thunderstorms. As warm, moist air rises and condenses, it releases energy that increases the wind speed as pressure decreases. As air rises faster and faster, it draws in air from the sea surface whilst pushing cooler air down. The speed increases, as they move over water and pick up more moist air.
• Scientists don’t know exactly how they are formed but they know the conditions needed:
  
  • A disturbance near the sea-surface triggers it (an area of low pressure).
  • Sea water that is warm (+ 27C for 50m down), so lots of evaporation and moisture (mainly from easterly trade winds).
  • Convergence of air in the lower atmosphere, either with the ITCZ or along the boundary between warm and cold air masses. This forces air to rise, then cool and condense and release latent heat, and as the air moves more violently it forms thunder clouds.
  • A location at least 5° from the equator (they don’t form 0-5° as the Coriolis effect isn’t strong enough there).
• So, they form in the tropics, as they are far enough from the equator, and still warm.
• They occur in the Caribbean Sea (hurricanes), the Bay of Bengal (cyclones) or in the China sea (typhoons). (Spatial distribution)
• They lose strength when they move over land (as their supply of warm moist air stops).
• They always move west due to the easterly winds in the tropics (trade winds in the Caribbean).
• They move away from the equator due to the Coriolis effect (caused by the Earth’s rotation).

Formation of the storms:

• They are circular in shape, 100s of kms wide and last from around 7-14 days. They spin anticlockwise in the northern hemisphere, and clockwise in the southern.
• At the centre of the storm is an area of very low pressure called the eye.
• Rising air spirals around the eye in the eyeball, causing strong winds.
• Near the top of the storm, there is an outflow of moisture-laden air, so cloud cover extends for a long distance either side of the eye.

Question 46

Storm Hazards:

Factors of storm hazards:

Answer 46

Storm magnitude is measured on the Saffir-Simpson Scale:

• They are classified based on wind speed. Category 5 is the strongest (with winds over 150mph) and 1 is the weakest (winds of over 74mph).
• It also estimates how much damage a storm of any magnitude will do, from limited damage (1) to catastrophic damage (5).

Frequency, regularity and predictability:

• Frequency: They are quite frequent, around 100 a year. But, most never reach land and so never become a major hazard. Storms are most common between June and Nov in the northern hemisphere, and Nov and April in the Southern. (Temporal distribution)
• Regularity: There are many factors that affect where and when a tropical storm will form and where it will hit land, so the hazards created by storms are largely irregular (they don’t follow a spatial or temporal pattern).
• Predictability: However, the path of a storm can be predicted accurately, by using satellite imagery to see cloud formations and wind patterns.

Question 47

Storm Hazards:

Forms of storm hazards:

Answer 47

Other forms of tropical storms:

• High winds: wind speeds on the ground can reach more than 300k/h. Wind can destroy buildings, uproot trees, and carry debris (cars and trees) long distances before smashing them into other objects.
• Storm surges: a storm surge is a large rise in sea level caused by high winds pushing water towards the coast and by the low pressure of a storm.
• Heavy rains: as warm, moist air rises it cools and condenses, causing torrential rains. EX: In 1996, over 1000mm of rain fell in 12 hours on Réunion island during cyclone Denise.
• Flooding: heavy downpours can cause river discharge to increase suddenly, causing rivers to overtop their banks and flood the surrounding area. Heavy rains and storm surges can also cause flooding on coastal areas.
• Landslides: water infiltrates soil and rock, making it less stable and increasing the risk of landslides.

Question 48

Storm Hazards:

Impacts:

Answer 48

Impacts (primary and secondary):

• Social:
  
  • People may drown, or be injured or killed by debris that is blown around or carried in flood water. (P)
  • Houses are destroyed, so people are left homeless. (P)
  • Electricity cables are damaged and supplies cut off. (S)
  • Flooding causes sewage overflows, contaminating water sources. (S)
  • The lack of clean water can help diseases spread. (S)
  • Damage to agricultural land can cause food shortages. (S)
• Economic:
  
  • Buildings and infrastructure cost a lot to rebuild. (P)
  • Businesses are damaged, or destroyed meaning they can’t trade. (P)
  • Agricultural land is damaged, so commercial farming is affected. (S)
  • The recovery effort will be a big economic burden. (S)
• Political:
  
  • People may blame the authorities for shortages of food, water and energy, leading to conflict and political unrest. (S)
  • Expensive repairs to buildings, infrastructure, etc, limit the amount of money that can be spent on development. (S)
  • International aid can create debt. (S)
  • A national state of emergency can create panic. (S)
• Environmental:
  
  • Beaches are eroded and coastal habitats (coral reefs, etc) are damaged. Sediment deposited in aquatic ecosystems may damage fish breeding areas. (P)
  • Environments are polluted, (e.g. by salt water, oil and chemicals) spilled by damaged factories. (S)
  • Landslides can block watercourses, so they change course. (S)
  • Disruption to salt marshes and ecosystems by adding more salt through coastal flooding. (S)

Question 49

Storm Hazards:

Responses (short/long term):

Answer 49

Responses:

• Short term:
  
  • These responses normally occur immediately before, during or immediately after the hazard.
  • EX: They include things like evacuating people from the at-risk areas.
• Long term:
  
  • Prevention: storms cannot be prevented, but they can be studied to help scientists understand which areas are most likely to be affected. This means that future developments can be planned to avoid high-risk areas (using govt legislation).
    
    • Protection against threat of storm surges, using artificial embankments, bypass floodways, flood storage areas.
    • Research into the effects of the storms to better prepare.
  • Preparedness: people and authorities can make sure they are prepared for a storm, e.g. emergency services can train and prepare for disasters, govts can plan evacuation routes to get people away from storms quickly and educate people about how to prepare for a storm (e.g. stockpiling water and food and boarding up windows).
    
    • Forecasting and warning systems needed, community education programmes, training of relief groups and emergency services. Stockpiling of food/water/ supplies. Emergency legislation for emergency help. Evacuation plans to escape high-risk areas, cyclone shelters built.
  • Adaptation: buildings can be designed to withstand tropical storms, e.g. by using reinforced concrete or by fixing roofs securely so they are not blown off. Buildings can also be put on stilts so they are safe from floodwater. Flood defences can be built along rivers (e.g. levees) and coasts (e.g. sea walls).

Question 50

Storm Hazards:

More examples of storm responses:

Answer 50

Aid (mitigation) and Insurance (mitigation)

What is it?

• Aid is when foreign nations and NGOs provide aid for LICs in the form of rescue, food/water, monetary and medical.
• Insurance is more of an important factor for HICs as insurance companies provide money for damaged property (this helps reduce the economic impacts of the storm).
• Insurance is primarily in HICs, because the insurance companies are almost entirely situated in HICs, due to their economic statuses. This also means that people in LICs are less likely to have insurance available to them as the companies will be less willing to support them, due to their lack of economic security.

How effective is it?

• Aid can be very effective and allows for LICs to recover from natural disasters that they would not have been able to recover from. However aid from countries can come with stipulations like deals for trade and greater dependence on HICs. Most NGOs provide stipulation free aid however it is on a smaller scale as they have lesser funding.
• Insurance is useful in HICs as the recovery from a natural disaster is shifted from the government to the general economy. While this can be beneficial for countries it can be very expensive in hazardous locations so poorer people can’t afford high premiums

Will it be suitable for every population?

• There is a strong and clear distinction that aid is primarily given to LICs, from HICs, as they lack the availability and reliability of insurance to help stem the economic impacts of storms.
• However, even some aid is not suitable for populations. This can be seen in the case of rural populations in LICs, as they are much less connected, the top-down aid distribution schemes are unlikely to reach them.
• Also, in terms of insurance, it is likely that the poorest or rural populations of HICs will be isolated from it. This is because the insurance companies are only likely to supply insurance to the most financially secure people, and the most connected people. They are unlikely to supply people with less financial security.
• They are also less likely to supply insurance to people living in high risk areas. For example, people living in New Orleans are less likely to be given insurance than people living in Washington D.C., as the former is far more at risk of tropical storms (Hurricane Katrina).

Examples:

• In Myanmar, Cyclone Nargis in 2008, over 135,000 people died. The survivors would likely not have had insurance as Myanmar is an LIC. However, they received aid from the international community. Mainly from Italy (supplying money and food), and also India (supplying supplies of temporary accommodation and funds). They received a total of over $350million.
• Whereas, in the USA with Hurricane Katrina, the city mainly affected (New Orleans) did not receive international aid, but instead the state of Louisiana received extra federal funding to help the aid effort, but the residents were primarily helped by insurance companies due to the USA being an HIC.

Structural Preparedness

1. What is it?
   * Involves designing, constructing, maintaining, and renovating physical structures and infrastructures to resist the physical forces of disaster impacts.
2. How does it help reduce impacts?
   * Elevating vulnerable buildings to reduce flood damage and designing structures to be resilient to high winds and flying pieces of debris might be future strategies to combat storm damage.
3. How effective is it?

• These techniques are expensive to put in place, however if they stop buildings being destroyed this saves money in the long-term as there is less need for rebuilding.
• Many of these developments require maintenance and are not a permanent solution thus contributing to the long-term costs.

1. Will it be suitable for every population?

• Most of the 10 major urban centres worldwide that are located in storm-surge zones are in poor countries (Malawi, South Sudan, Niger, Mozambique). This highlights the potentially deadly exposure of their inhabitants, since storm water drainage infrastructure is often outdated and inadequate. The risks may be particularly severe in poor neighbourhoods and slums, where infrastructure is often non-existent or poorly designed and ill-maintained.
• Solutions such as The Climate Tile are not suitable to less developed regions where there is not already a pre-existing underground network of pipes to disperse the water.
• In regions where there is internal conflict or government corruption, it is more likely to be the case that these mitigation techniques are not suitable or plausible. (E.g. Syphoning money from development funds to finance war).

1. Examples of it

• Design buildings with secure roofs which use reinforced concrete. Concrete is strong, durable, readily available, fire resistant, and will last a very long time. Buildings are less likely to be destroyed, so less people will die from collapsing buildings and falling debris.
• Build levees (along rivers) or sea walls along the coast. Levees are natural or artificial walls that block water from going into the sectioned off land. This reduces the risk of flooding from overflowing rivers, or from storm surges.
• Swales - an area of land that is lower down - create a natural barrier to keep water away from a house or building. By building up the land close to the house you have lower areas around the high point that can divert water away from the house.
• Houses with steel frames are non-combustible and not prone to the frame becoming damp from exposure to water. Houses using a steel frame must be properly insulated especially if in a region with a cold climate; however, are generally the better alternative disregarding the higher costs.
• The most desirable sites for seawalls tend to be low lying urban areas where there are many high-valued vulnerable buildings. However, economic studies suggest the optimal height of such seawalls is well below the height of the surge from a major tropical cyclone. Studies found that the additional cost of raising seawalls high enough to stop the surge from a major hurricane is far more than the additional expected flood benefit.

Stilt houses (Assam, India)

• Every year, floods occur in the basin of the Brahmaputra and its tributaries. Low-lying areas like Golaghat, are flooded by water spilling over its banks during the monsoon. Communities build their houses on stilts to let the floodwaters flow below and they profit from the fertile silt left behind when the floodwaters receded.
• Embankments keep being damaged or washed away altogether whenever a large flood occurs. With more severe weather due to climate change embankments are posing a problem as they cannot stop the floodwaters from submerging the land, yet they stop floodwaters from receding back into the rivers. This way the land remains waterlogged much longer than it would have otherwise.
• Dams hold back or divert almost all the water in almost all the rivers of the basin now. In recent years, dam managers have been forced to open the gates every monsoon to save the structures – leading to a more ruinous flood pulse than would have occurred otherwise.
• Additionally, silt (a fertile sediment used to rejuvenate farmlands) is stopped behind dam walls, floodwaters only scour out the riverbanks without building fresh land with the silt.

The Climate Tile (Denmark)

• The Climate Tile, a type of pavement tile used in the Nørrebro district of Copenhagen, Denmark. Example of urban planning that is trying to mitigate flooding from heavy rainfall, in this case by using a system of holes and tunnels that converge water to areas of vegetation. Clearly the magnitude of flooding in Denmark is much lower than that experienced by people in, for example, Puerto Rico last year after Maria hit their coasts. The way the architecture of a city has to change will be a consequence of the socio-political commitment of the country it is in - eg, if architectural designs and urban planning represent a valid way to resist destruction, political and social commitments need to be made to make this a realistic option.

The MOSE (Venice)

• Storm surge gates and flood barriers such as the Thames Barrier (closes off the Thames river just east of the city of London), and the Venice barriers, aka the ‘MOSE’.
• The MOSE: been in development stages since 1984. Took nearly four decades to build, being beset by delays and corruption to such an extent – a former mayor went on trial for embezzling money from the project – that many Venetians believed it would never work. Made up of 78 barriers (20-30 metres long and 20 metres wide), spread in four lines, at the three entry points to the Venetian lagoon.They are embedded in the seabed in concrete chests. Unlike flood barriers in northern Europe – and at much greater expense – the MOSE was designed to be invisible when the barriers are not in use. So far it has been raised 33 times.

The Afsluitdijk Project (Netherlands)

• The outer side of the dyke will be covered with new cladding. The plan is to make the dyke overflow-resistant, meaning that water can flow over it during a heavy storm and the inner side of the dyke will be able to cope with the encroaching water.
• Modifications to strengthen the sluices: installing floodgates to protect the navigation locks when water levels rise too high; replacing the sluice gates; strengthening the artificial islands and the jetties; increase the discharge capacity by installing pumps in the discharge sluices at Den Oever so that water can be discharged even when the water level in the Wadden Sea is high.

Adaptation - How effective it was

Sea walls may threaten the tourism industry because they change landscape, ecosystem health and beach leisure attractions. Coastal attractiveness for leisure and tourism activities is closely linked to various parameters such as landscapes, the quality of the environment, water availability, ect. Consequently, in some contexts, hard protection would simply not be an option

Question 51

Storm Hazards:

Case Studies:

• *1. Hurricane Matthew 2016 (Caribbean and eastern USA)**
• *2. Cyclone Winston 2016 (Fiji)**

FOR MORE INFO ON THIS, CHECK THE SHARED CLASS DOC ON FILES

Answer 51

1. Where did it happen and when? What caused the hurricane and what was its path?

Hurricane Matthew was a category 5 hurricane that wrecked the eastern Caribbean Sea and western Atlantic Ocean during September and October 2016. It directly affected Haiti, Cuba, the Dominican Republic and the South-eastern USA. The two most affected nations were Haiti (estimated 546-16000 deaths) and the USA (47 deaths).

It was caused when in late September 2016, a tropical wave formed near the Cape Verde Islands and blew west through the Atlantic via the Trade Winds, and strengthened until it became the Tropical Storm Matthew as it neared the Caribbean.

It first hit land in Haiti, then moved up through Cuba, into the Bahamas (coming only 40km away from the capital of Nassau), then moving past Florida (right next to the coast, but not hitting land). It then hit the USA for the first time in South Carolina.

Cyclone Winston was a category 2 cyclone that was expected to pass west and south of Viti Levu Island and across the Vanua Levu Island on the 6^th-7^th April 2016. On the 4^th April, integrated mobile outreach activities reached communities and outreach teams launched to prepare the population.

1. What were the primary impacts and which was the greatest impact?

Hurricane Matthew:

• There were torrential rains, storm surges and winds up to 145mph.
• Floods in the Dominican Republic killed 4 people.
• Although the storm did not directly hit North Carolina, there was considerable flooding that damaged the area.
• Extensive preparation took place, with over 1 million Cubans evacuated.
• Storm surges reached as high as 9 feet
• Flooding and sand dune damage was significant in Jacksonville.

Cyclone Winston:

• Sustained winds of up to 230mph, 40% of the population lives within 50km of the centre of the cyclone, with very destructive force winds.
• 44 confirmed deaths
• A series of tropical depressions caused flooding in the North and West of Fiji and heavy rain.

1. What were the secondary impacts and which was the greatest impact?

Hurricane Matthew:

• Left over 1.4 million people in need of humanitarian aid.
• Power outages, crop damage, landslides in some islands of the Lesser Antilles.
• In Haiti, there were estimated damages of up to $2.25billion and 1600 deaths.
• 80% of the buildings in Jeremie (Haiti) were destroyed.
• In the Bahamas, there was considerable damage to buildings, with over 95% of buildings on the island of Grand Bahama being damaged (although no fatalities reported).
• Over 1 million people in Florida lost power, and over 500,000 in both Georgia and South Carolina.
• Florida, Georgia, South Carolina and North Carolina were all put under a ‘State of Emergency’.
• A total of 4,500 flights were cancelled, with the closure of airports at Orlando and Fort Lauderdale. Also tourist sites like Disney World and Universal Studios.
• Over 2 million people were forced to leave their homes (through evacuation measures).
• A poorly built orphanage collapsed, and all the children inside were reported to be dead.
• In some areas of Haiti over 90% of homes were destroyed.
• Farming, fishing and small-scale commercial activities were not able to continue (economic impacts, leading to loss of income and livelihoods).
• There was considerable damage to critical water and sanitation infrastructure that contributed to an increase in cholera cases.

Cyclone Winston:

• Ministry of education closed schools and instructed that all temporary learning buildings dismantled to avoid cyclone damage.
• Stopped many ships docking in the ports, and therefore stopped many imports from arriving, which is how they get their food.
• Farming and fishing was also halted.

1. Responses (long and short term)

Hurricane Matthew:

• 80% of money aid to Haiti is thought to have been used by donors to launder their money.
• There was a campaign to re-habilitate the image of several NGOs that did not work effectively in the 2010 Haiti earthquake.
• Red Cross gave aid to Haiti (around $300mill)
• US gov gave $100 mill to Haiti
• 9,100 sheets of re-enforced plastic were given to provide temporary shelter.
• Improve departmental emergency operations.
• Road rehabilitation: around 900,000 feet of debris cleaned and road access created
• Short term: mass evacuation of the coastal areas.

Cyclone Winston:

• 79 evacuation areas, due to flooding, 6^th April all schools were closed.
• Wellbeing of 30,000 households destroyed by tropical cyclone
• Elderly people were evacuated and joined relatives for safety.
• Increased risk of vector-borne diseases (Malaria)
• Pacific Humanitarian Partnership, a group co-ordinated by the UN office for coordination of humanitarian affairs is supporting gov ministries.

Question 52

Wildfires:

The nature of wildfires

Answer 52

Definition: Wildfires are uncontrolled fires in areas of combustible vegetation, that occurs in the wilderness or countryside, destroying forests, grasslands and other vegetation, as well as any settlements in their path.

Definition: ‘The fire front’, is the portion sustaining continuous flaming combustion, where unburned material meets active flames.

• There are 3 types of wildfire:
  
  • Ground fire: where the ground itself (peat and tree roots) burn. It is a slow, smouldering fire with no flame and little smoke.
  • Surface fire: where leaf litter and low-lying vegetation burns. Fire can be low or high intensity.
  • Ladder fire: where the surface fire rises higher (potentially becoming a crown fire), due to the burning of vines or exposed bark-less trees.
  • Crown fire: where fire moves through the canopy rapidly. These are intense and fast-moving.
• Wildfires are always unique, but differ from other fires due to their extensive size, their speed of spreading from the source, its potential to change direction unexpectedly, its ability to jump gaps (rivers, roads, fire breaks, etc), their cause of ignition, their fuel and the effect of weather on the fire.
• There are around 60-80k fires in the UK each year, burning 3-10million acres of land.

Question 53

Wildfires:

Conditions for intense wildfires to start:

Answer 53

Optimal wildfire conditions for intense fires:
- They need all three elements to start: Fuel, oxygen and heat.

• Vegetation type:
  
  • Thick undergrowth or closely packed trees allow fires to travel easily.
  • Some trees, like eucalyptus and pine, contain a lot of oil and so burn easily.
  • Eucalyptus trees shed strips of their bark which helps fires spread quickly.
• Fuel characteristics:
  
  • Fine, dry material (long grass, thin twigs) catch fire and burn most easily. The high evapotranspiration levels for the vegetation and lack of moisture input dries out the fuel and makes burning easier.
  • Large amounts of fuel that form a continuous cover will help the fire burn for longer and spread easier.
• Climate and recent weather:
  
  • Rainfall must be sufficient for vegetation to grow, so there is plenty of fuel.
  • The area usually has a stint dry season when rainfall is low for a significant amount of time. Warm and dry weather causes water in the vegetation to dry up, so its more flammable.
  • Strong winds provide more oxygen to help the fire burn and spread burning embers (16% oxygen is required as it supports the oxidation process, creating heat and gases).
  • Climate changes, like heat waves, droughts, el Nino, and regional weather patterns like high-pressure ridges increase the risk and alter the behaviour of wildfires.
  • Wildfires are far more likely in the daytime (5x more chance, due to low humidity, increased temps and wind speeds).
• Fire behaviour:
  
  • Fire burns in different ways - e.g. creeping fire moves along the ground surface slowly, whereas running fires are faster and more intense.
  • Fires can throw out burning debris (firebrands) that help the fire spread and become more intense.

However, some natural wildfires are needed to maintain the balance of the ecosystem.

• *Also, some vegetation is adapted:**
• Eucalyptus trees have sclerophyll leaves that are heat and drought resistant.
• Some pioneer species have seed and shoots that are stimulated to germinate when they sense smoke and heat (serotiny process).

Question 54

Wildfires:

Causes:

Answer 54

Fires need fuel (vegetation), oxygen (16%) and a heat source (which can be natural/human).

• Natural causes:
  
  • Lightning is likely to start a fire if it occurs without rain.
  • Volcanic eruptions can produce hot lava, ash or gases which start fires (or hot rock bombs also do).
  • Sparks from rockfalls.
  • Spontaneous combustion.
  • Coal seam fires (underground burning of coal), can reach the surface and start wildfires.
• Human causes:
  
  • The majority of fires are human caused.
  • This can be accidental (e.g. cigarettes, allowing campfires/barbecues/fireworks to get out of control, or sparks from machinery or electricity wires can start them, or the sun being magnified by glass/plastic). This also includes slash and burn farming getting out of control.
  • Or on purpose (arson).

In the USA, there are 6x more human caused than natural caused wildfires a year. However, the naturally caused fires sometimes burn more acres (2million vs 1.4million in 2010 USA).

Question 55

Wildfires:

Impacts (primary and secondary) NOT IN COURSE:

Answer 55

• Social:
  
  • People are killed/injured if they don’t evacuate.
  • Homes are destroyed, and people left homeless.
  • Power lines and reservoirs destroyed, leaving people without water and power.
  • Can cause health issues (respiratory problems through smoke inhalation).
• Economic:
  
  • Destruction of businesses, leading to unemployment and less income/economic stimulation.
  • Insurance premiums increase after fires.
  • Cost of fighting the fires is huge, and the recovery effort.
  • Tourism may be damaged out of fear.
• Political:
  
  • Govts face criticism when fires have big impacts.
  • Govts may have to change their forest management practices to reduce the risk of fires.
• Environmental:
  
  • Habitats destroyed, some species wont return and this changes the ecosystem.
  • Soils are damaged and become infertile.
  • Smoke causes air pollution and water sources can be contaminated by ash.
  • Although, it is good for some ecosystems that need it to clear dead wood and stimulate germination in some plants.

Question 56

Wildfires:

Responses (short and long term):

Answer 56

• Short term:
  
  • Trying to put out the fire, diverting it away from settlements.
  • Evacuating people from at-risk areas.
  • Spraying water onto the houses to prevent embers from re-lighting the fire.
• Long term:
  
  • Prevention: education of the public to avoid human caused fires. Authorities can provide equipment like fire beaters to put small fires out to avoid them spreading.
  • Preparedness: households having an emergency plan and emergency supplies of food, water and medicine. Authorities can make emergency shelters available.
  • Adaptation: individuals and authorities change to cope with the fires, by using non-flammable building materials, adding cladding, creating fire breaks (gaps in trees) around settlements to contain future fires.

Answer 57

Technique: Aeroplanes and helicopters are used for air drops where water and fire-retardant chemicals and water are released from the aircraft onto the wildfire.

• Advantages:
  
  • It slows the fire’s progress and lessens the intensity so ground crews can approach. This is particularly effective in smaller fires that can be covered. It is speedy, as aircraft are fast and many can be used at the same time. The planes can also alter their strategy to where the wildfires move quickly. They can also bypass blockages of debris that would mean vehicles wouldn’t be able to access the area.
• Disadvantages:
  
  • The chemical used is called Phos-Chek, it can spur algae blooms, kill fish and other animals (mostly marine). Sometimes they spray it on protected wildlife areas. It is especially harmful in concentrated ecosystems (e.g., where a species only lives in one area). It also adversely affects water quality of the area. You need highly skilled pilots, and the flights are very dangerous.

Technique: Wildland fire engines use special equipment to spray water, foam and chemicals. The engines are able to carry up to 800 gallons of water. Many wildland fire engines are also equipped with four-wheel drive and special equipment for off-road use.

• Advantages:
  
  • Better access in comparison to normal city fire trucks, you can pin-point fires (particularly small fires). You can utilise many of these trucks for the same price as buying planes or helicopters. More people can be utilised on the ground than in the air.
• Disadvantages:
  
  • Only a small amount of water can be carried, and there is no ariel advantage that allows you to see the fire and alter to its path.
  • Also, if you are using planes, then chemicals can be harmful to ground crews.

Technique: Smokejumpers parachute directly into the wildfire and carry axes and small amounts of fire-retardant gel.

• Advantages:
  
  • It is good for the ecosystem, cheap
  • Can stop fires from jumping lines or breaks as people are there stopping it.
• Disadvantages:
  
  • Dangerous!
  • Small scale, as it is not very appliable to large scale fires.

Technique: Control lines may be built to reduce the amount of fuel available for the fire. This is achieved by removing potential fuels and using natural barriers such as rivers and terrain breaks. This may be done by hand with tools called ‘pulaskis’ or with bulldozers.

• Advantages:
  
  • Pro-active rather than reactive. This can be done beforehand, and reduces the size of the future fires. No deaths and is quite cheap.
• Disadvantages:
  
  • There will still be a fire, just maybe to a lesser extent.

Technique: Backfiring is used to deliberately burn areas of land ahead of the fire and use up the fuel. This is controlled by the firefighting services. Bulldozers may be used for large areas.

• Advantages:
  
  • Controlled and much more strategic. Based on the idea that some controlled wildfires are good for the ecosystems.
• Disadvantages:
  
  • Labour intensive and dangerous to humans
  • Can have accidents and create big wildfires

Techniques: Mandatory evacuations are used when wildfires are becoming a risk to homes. People are moved to a safe area and sometimes the evacuations are enforced by law.

• Advantages:
  
  • Saves many lives
• Disadvantages:
  
  • Still damages buildings and the trees. This is an attitude of acceptance that there is nothing to do to protect the area. Instead, they just accept it will happen and then respond to the natural impacts after avoiding death.
  • Also, the physical and psychological impacts of losing a home or property (sense of place, and connections).

Technique: Volunteer groups help to remove dead leaves and branches from areas at risk. Park services also display advertising campaigns designed to increase awareness on how to prevent wildfires.

• Advantages:
  
  • Utilises a lot of people doing a small amount individually, but large impact collectively. Bottom-up approach and cheap
• Disadvantages:
  
  • Wildfires still happen. By utilising volunteers, you have to question when they should stop and get professionals to do the job as a trained person.

Technique: GIS (Geographical Information Systems) are being developed to show the extent of wildfire potential. They might show factors such as climate, drought potential and amount of fuel wood in a particular area and are used to forecast impending wildfires.

• Advantages:
  
  • Highly strategic, you can focus resources in the correct areas as a result of the data. Going back to allowing fires to take some areas, will be better in the long run, and this programme can be used to support this idea and plan
• Disadvantages:
  
  • Doesn’t directly stop fires and mitigate damages, and it is also a privately owned service and so authorities wanting to use it will face political and free-market issues to be able to use it.

Question 58

Wildfires:

Case Study: South Eastern Australia Wildfires 2009

Answer 58

• In Feb 2009, severe wildfires burned for a month in the state of Victoria in SE Australia. The worst fires occurred in the forested areas.
• Environmental conditions added to the intensity of the fires - they followed 10 years of drought, recent temps had been over 40C and there were strong winds.
• Lack of management: (e.g. lack fo controlled burning of forest litter), meant that there was a large amount of very dry, oil-rich material to fuel the fire. Several of the fires were caused by faulty power lines.

There were severe impacts, despite management attempts:

• 173 people were killed and around 400 injured. Many more suffered from stress and depression as trauma.
• 2,000 homes destroyed in over 78 communities.
• More than 60 businesses were destroyed, causing unemployment and loss of income and economic stimulus to the area.
• The total estimated cost of the fire was around $3bn.
• Around 4300km² of land was burned, including forest and national parks. Millions of animals and reptiles were killed, including some rare species such as the spotted tree frog.

Responses (short and long term):

• The Australian Bureau of Meteorology predicted how the fires would spread and told residents that they could either evacuate or stay and defend their homes. Evacuation reduced the number of deaths, but many people were put at risk by choosing to stay in their home.
• More than 20,000 firefighters and volunteers helped to put out the fires and support victims.
• More than $300million was donated to help rebuild houses and community facilities. However, making new homes more fire-resistant increased costs, so not everyone could afford new homes, creating some homelessness/poor quality housing.
• Recommendations for long term responses include building fire shelters in vulnerable areas, improving warning systems and improving the emergency evacuation strategies.

Question 59

Wildfires:

Characteristic Human Responses to Wildfires:

Attitudes towards wildfires:

Answer 59

Fatalism:

A defeatist attitude of acceptance that wildfires are natural or acts of God, and we cannot control them. Interference could be detrimental. Nature must be able to take its course and losses must be accepted.

Domination/Prediction:

As technology increases, the methods of predicting wildfires become more advanced. This can help us predict and dominate the effects of wildfires and overcome them, stopping deaths from occurring.

Adaptation:

Once we accept that wildfires are inevitable to some extent, we can adapt our behaviour so that losses can be kept to a minimum.

Question 60

Wildfires:

Characteristic Human Responses to Wildfires:

Perception of wildfires:

Answer 60

People’s perceptions of wildfires is affected by their economic, social and cultural backgrounds. Factors include:

• Wealth: Richer people may be able to move to areas that are less prone to wildfires, or to build fire resistant homes to withstand the fires, so they will perceive the wildfires as less of an issue.
• Religion: Some people view wildfires as acts of God, sent to take their natural course.
• Education: People with more education may have better understandings of the risks posed by wildfires, or they believe that they can reduce the risks or mitigate the impacts.
• Past experience: People who live in wildfire-prone areas may have experienced wildfires before, which may affect the perceived risks of future fires.
• Personality: Some people fear wildfires, and other might think of them as exciting.

Individuals and govts might try and respond to a wildfire to reduce their vulnerability/their country’s vulnerability or reduce its impacts.

• People may try and prevent a wildfire or reduce its magnitude. This is possible for wildfires, unlike volcanoes or EQs.
• Risk sharing involves sharing the costs of reducing the wildfire in the community, the benefits of preventing it, or the consequences of not preventing it. (E.g. people buy insurance to help them repair property after the wildfire). Most people wont be affected by the fire, so they won’t claim insurance, which means a lot of people contribute and the cost is shard.
• People may try and reduce (mitigate) the impacts of a wildfire. This could be by prediction - working out when and where a wildfire is likely to occur, which allows people to respond to it (by evacuating and area). It can also be by adaptation (adding wildfire resistant features to buildings/doing controlled burning).
• Govts can coordinate responses to a wildfires to manage them effectively.
• Some people believe that wildfires can’t be avoided, so they must be accepted (fatalism).

The success of attempts to manage wildfires depends on their incidence (how often), magnitude/intensity (their power) and distribution (the areal extent of the hazard). Generally, wildfires with low incidence and high magnitude are most destructive. The level of development is also important - less developed countries may lack the wealth and technology to manage wildfires effectively.