Geography Edexcel - Tectonics

The IMPACTS of tectonic hazards are broadly of three types:

1. Social - deaths, injury and wider health impacts including psychological ones
2. Economic - the loss of property, businesses, infrastructure and opportunity
3. Environmental - damage or destruction of physical systems, especially ecosystems

·       Volcanic eruptions: Small and declining impacts, especially death tolls

·       Earthquakes: Large impacts, as significant earthquakes are common and widespread

·       Tsunami: Very large impacts from a small number of events

Comparing impacts between countries is difficult because both the physical nature of the event and the socio-economic profiles of affected places are different. Some general observations are:

• economic costs in developed and emerging economies are, in some cases, enormous
• deaths in developed countries are low, except for the 2011 Japanese tsunami
• volcanic eruption impacts are small compared with those of earthquakes and tsunami

Factors such as population density, duration of ground shaking, secondary hazards and response are also important. Generally, low level of development increases risk by increasing vulnerability:
Increasing risk:

• Population growth
• Urbanisation and urban sprawl
• Environmental degradation
• Loss of community memory about hazards
• Very young, or very old population 
• Ageing, inadequate infrastructure
• Greater reliance on power, water and communication systems

Mitigating risk

• Warning and emergency-response systems
• Economic wealth
• Government disaster-assistance programmes
• Insurance
• Community initiatives
• Scientific understanding
• Hazard engineering

In some locations with very low human development (below 0.55), vulnerability is usually high because:

• many people lack basic needs of sufficient water and food even in 'normal' times
• much housing is informally constructed with no regard for hazard resilience
• access to healthcare is poor, and disease and illness are common
• education levels are lower, so hazard perception and risk awareness is low

In rural Nepal, the area hit by the 2015 earthquake, 40% of families live below the poverty line and more than 90% depend on subsistence farming. Of the rural population, 40% exhibit stunting of growth as a result of malnutrition and only 20-40% of rural adults are literate. 

Governance refers to the process by which a country or region is run.The effectiveness of governance varies enormously and has a significant impact on coping capacity and resilience in the event of a natural disaster. The link between governance and vulnerability:

1. Meeting basic needs – When food supply, water supply and health needs are met the population is physically more able to cope with disaster
2. Planning - Land-use planning can reduce risk by preventing habitation on high-risk slopes, areas prone to liquefaction or areas within a volcanic hazard zone
3. Environmental Management - Secondary hazards, such as landslides, can be made worse by deforestation. The right monitoring equipment can warn of some hazards, such as lahars. 
4. Preparedness - Education and community preparation programmes raise awareness and teach people how to prepare, evacuate and act
5. Corruption - Siphoning off money ear-marked for hazard management or 'kick-backs' and bribed to allow illegal or unsafe buildings increase vulnerability. Kickback = illicit payment made in exchange for facilitating a transaction
6. Open-ness - Governments that are open, with a free press and media, can be held to account, increasing the likelihood that preparation and planning take place. 

Most countries have national disaster management agencies, such as FEMA in the USA, which increase resilience to hazards and reduce the impacts of disasters. In the developing world these can be effective, such as PHIVOLCS in the Philippines, but they are often under-funded and under-resourced. 

Low-level corruption of local government officials is common in many developing countries, meaning that building codes are often ignored and construction allowed in inappropriate places. This was widely blamed for the high death toll of 17,000 in the Izmit earthquake in Turkey in 1999.  

The nature of tectonic hazard impacts is influenced by several geographical factors, including:

• Population Density: highly populated areas may be hard to evacuate, such as the area around Mt Vesuvius in Italy, and are likely to be hit harder by an earthquake 
• Degree of Urbanisation: when cities are struck by major earthquakes, such as the 1995 Kobe earthquake in Japan or Haiti in 2010, death tolls can be high because of the concentration of at-risk people. 
• Isolation and Accessibility: often rural areas are hit less hard than urban areas by the initial impact of the disaster, but isolation and limited access can slow the rescue relief effort. The 2005 Kashmir earthquake is a good example. 

Urban areas usually have more assets than rural areas. These include hospitals, emergency services, food stores and transport connections, which increase resilience and coping capacity compared with isolated rural places. However, high population density may mean more people are affected. 

Volcanic eruptions

• Can be predicted
• Sophisticated monitoring equipment on volcanoes can measure changes as magma chambers fill and eruption nears
• Tiltmeters and strain meters record volcanoes 'bulging' as magma rises and seismometers record minor earthquakes indicating magma movement
• Gas spectrometers analyse gas emissions which can point to increased eruption likelihood. 
• The minimal death toll from volcanic eruptions (despite 60-80 eruptions per year) can be mainly attributed to vastly improved prediction of these events. 

Tsunami

• Can be partly predicted
  • An earthquake-induced tsunami cannot be predicted
  • However, seismometers can tell an earthquake has occurred and locate it, then ocean monitoring equipment can detect tsunami in the open sea
  • This information can be relayed to coastal areas, which can be evacuated.

Earthquakes

• Cannot be predicted (despite decades of scientific research)
  • Only areas at high risk can be identified (risk forecasting), plus areas that are likely to suffer severe ground shaking and liquefaction; this can be used for land-use zoning purposes
  • 'Seismic gaps', i.e. areas that have not experienced an earthquake for some time and are 'overdue' can point to areas of high risk

Prediction, when possible, is a vital part of attempts to manage the impacts of natural disasters. However, it is not the only approach. The hazard management cycle illustrates the different stages of managing hazards to reduce the scale of a disaster. It is a cycle, with one disaster event informing preparation for the next.

 The 'Recovery' Stage of the Hazard Management Cycle might be thought of as the 'returning to normal' state. This can happen after a few months, but in some cases, it takes years. The recovery stage depends upon:

The magnitude of the disaster - bigger means longer

Development level - lower means longer, as poorer people are more severely affected

Governance - because well governed places will divert resources more effectively to recovery efforts.

External help - i.e., aid and financing to help the recovery effort

Land-Use Zoning

This is preventing people from building:

• on low-lying coasts (at risk from tsunami and flooding)
• close to volcanoes
• on areas of high ground-shaking and liquefaction risk

Advantages

• Low cost
• Removes people from high-risk areas

Disadvantages

• Prevents economic development on some high-value land, e.g., coastal tourism
• Requires strict, enforced planning rules

Aseismic Buildings

Buildings that are strong enough to resist (most) earthquakes and prevent damage. They may include:

• cross-bracing
• reinforces structures, since one diagonal brace may be in tension whilst the other is slack
• counterweights
• deep foundations
• these may be of stone, and made from rubble
• hollow concrete bricks designed to cause minimal damage
• reinforced cement concrete roof
• reinforced steel corner pillars to provide strength and flexibility

Tsunami Defences

Tsunami sea walls and breakwaters, which prevent waves travelling inland. 

Advantages

• Dramatically reduces damage
• Provides a sense of security

Disadvantages

• Can be overtopped
• Very high cost
• Ugly and restrict use/development at the coast

Lava Diversion

Channels, barriers, and water cooling used to divert and/or slow lava.

Advantages

• Diverts lava out of harm's way
• Relatively low cost

 Disadvantages

• Only works for low VEI basaltic lava
• Most 'killer' volcanoes are not of this type

Hi-Tech Scientific Monitoring (used for Prediction)

This is used to modify the behaviour of volcanoes and predict eruptions. 

Advantages:

• In most cases, predicting an eruption is possible
• Warnings and evacuation save lives

Disadvantages

• Costly, so not all developing world volcanoes are monitored
• May suffer from 'cry wolf syndrome' if predictions are not accurate
• This is where predictions (and evacuation) are wrong, so people are less likely to believe the next one. 
• Does not prevent property damage

Community Preparedness and Education

Examples of this are: preparation days, education in schools and earthquake kits. These are boxes of essential household supplies (water, food, battery powered radio, blankets) kept in a safe place at home to be used in the days following an earthquake. 

Advantages

• Low cost, often implemented by NGOs
• Can save lives through small actions

Disadvantages:

• Does not prevent property damage
• Harder to implement in isolated rural areas

Moving out of harm's way and relocating to a safe area. 

Advantages

• Would save both lives and property

Disadvantages

• High population densities prevent it
• Disrupts people's traditional homes and traditions

Loss modification could be described as 'picking up the pieces' after a disaster has occurred. Losses should be small if event and vulnerability modification have been used, however loss modification is often the main management strategy in developing countries. This was the case after the 2010 Haiti earthquake and the 2004 Indian Ocean tsunami, where management failed to protect people.

 Short-term Emergency Aid= Search and rescue followed by emergency food, water and shelter.

Advantages

·       Reduces death toll by saving lives and keeping people alive until longer-term help arrives

Disadvantages

·       High cost

·       Difficult to distribute in isolated areas

·       Emergency services are limited and poorly equipped in developing countries

Long Term Aid

Advantages

·       Reconstruction can 'build in' resilience through land-use planning and better construction methods

Disadvantages

·       Very high costs

·       Needs are quickly forgotten by the media after the initial disaster

Insurance

Advantages

·       Allows people to recover economically by paying for reconstruction

Disadvantages

·       Does not save lives

·       Few people in the developed world have insurance.