Tectonics

    Cards (62)

    • Natural hazards:A hazard is something that is a potential threat to human life or property
      • Natural hazards can be divided into three types
      1. Geophysical hazards: caused by processes in the lithosphere. Includes tectonic hazards, e.g. earthquakes, volcanic eruptions, landslides and tsunamis 
      2. Atmospheric (or hydrometeorological) hazards: caused by climatic processes. Include tropical cyclones, storms, droughts, extremes of hot or cold weather and wildfires 
      3. Hydrological hazards: caused by water movement. Includes floods and tsunamis
    • Disaster:
      • A disaster is when a hazard occurs and has significant impact on a population 
      • A threshold a disaster happens will be different for different countries, e.g. a hazardous event may be considered a disaster when there are: deaths of 10 or more people, 100 or more people affected at least US $1 million lost economically
      • A mega disaster has a regional or global impact 
      • Different countries or communities will define a disaster differently, they are said to have occurred when countries or communities can no longer cope with the challenges that the hazardous event has created
    • Threshold is the intensity or magnitude level natural hazard would have to surpass to be considered a disaster
    • The Degg model suggests that a disaster occurs where a natural hazard event meets a vulnerable population. The greater the natural hazard event, and the more vulnerable the people, the greater the disaster 
    • Resilience is the capacity for a community to cope with and recover from a natural disaster. This indicates any system in place to manage a natural hazard once it has occurred, and any pre-planning done to reduce the number of people at risk
    • Vulnerability is the level to which a community or geographical area will be damaged or affected by the occurrence of a hazard. The vulnerability of a community relates to its level of hazard preparedness 
    • Different communities experience the impacts of disasters in very different ways. This is largely due to different places having different levels of development 
      • Some communities have a higher level of resilience due to their awareness of natural hazard risks. They may acknowledge potential hazards and act to limit the damage that a natural hazard event could cause
      • Communities that have a low resilience and high vulnerability will have a lower disaster threshold. This means a hazard is more likely to be a disaster in that community
    • The vulnerability of a community can be determined by the factors below:
      • Location in relation to topographical features 
      • Location in relation to the site of the hazard
      • Isolation from/access to other communities 
      • Age and gender structure of their population
      • Level of urbanisation and population density  
      • Degree of poverty/wealth of population
      • Level of education and literacy rate
      • This means that the vulnerability of a community to natural hazards can be determined before a natural hazard occurs 
    • A risk of potential exposure to a disaster. Risk is a complex idea based on a country’s vulnerability, resilience and the nature of the hazard itself. The unpredictable nature of hazards means that there is always an element of risk, and so people always have a degree of vulnerability 
    • The Hazard Risk Equation is a way of trying to quantify the different factors at play in determining the risk that a natural disaster poses. Countries are at a greater risk if they are more vulnerable or if the intensity of the hazard itself is greater too 
      • In a similar way to the Degg model, increases in the magnitude of the hazard will increase the risk of a disaster. Equally, if the population becomes more vulnerable, the risk and intensity also increases.
    • Factors which increase the risk of a hazard:
      1. Size of the affected area
      2. Duration it is experienced for
      3. Level of intensity or magnitude 
      4. Speed of onset (how quickly it happens)
      5. Time of day/season
      6. Frequency 
    • Its difficult to stop a hazard occurring, for example we can’t prevent an earthquake. This means that governments tend to look at reducing a country’s vulnerability level in order to better manage hazards
    • PAR model (1)
      • The Pressure and Release model (PAR) explains a hazards socio-economic context and the combination of conditions in which a disaster could emerge 
      • It suggests that there are certain root causes of vulnerability that create dynamic pressures (stresses on a population) which in turn lead to unsafe conditions when a hazard occurs. All of these develop a picture of a country's vulnerability to a natural hazard. 
      • It also shows that nature of the hazard itself has a large part to play in whether a disaster is declared
    • PAR model (2)
      • The pressure in the title of the model comes from the idea that there is increased stress from both causes of the disaster, the natural hazard itself, as well as a layer of vulnerability. When either becomes too much, a disaster happens. In order to release the pressure, either the nature of the hazard or the degree the vulnerability needs to be reduced 
      • The PAR model highlights the importance of a country’s economic development to its risk of experiencing a disaster.
      • Many root causes for vulnerability are less likely to be a problem in developed countries  
    • The World Risk Index measures the level of vulnerability and exposure to hazards in different countries. Its an index score based on four factors 
      1. Exposure to hazards 
      2. Susceptibility to the impact of hazards 
      3. The capacity to cope with the impacts of hazards 
      4. The capacity to adapt to the impacts of hazards 
      When compared with the income level, you can see a correlation between this and vulnerability 
    • Inequality (1)
      • Inequality is the unequal distribution of monetary and physical resources
      • A country’s level of vulnerability and resilience to natural hazard events often reflects its levels of economic, political, cultural and social development 
      • Countries with a low level of development and a low score in the Human Development Index are more vulnerable and have an increased risk of experiencing a disaster 
    • Inequality (2)
      • Where there are limited public funds, authorities are more likely to spend finances on short term urgent problems rather than long term hazard mitigation strategies. These are often very expensive and may not be need for some time 
      • Pre-existing issues within a developing country, such as drought, external debt or civil unrest, can increase the country’s vulnerability when a natural hazard occurs
    • Increased vulnerability and reduced resilience may be caused by inequalities in Education (1)
      • Populations with less access to education have a reduced chance of perceiving and understanding hazard risks 
      • They may be unable to read leaflets and posters or lack access to public information systems, such as radio broadcasts, that advise them of safe practices. This means that when a natural hazard occurs, they are less likely to know how to react to the hazard and may make decisions which endanger their lives 
    • Increased vulnerability and reduced resilience may be caused by inequalities in Education (2)
      • Populations with low levels of education may view the ideas of experts and scientists as suspicion. When a natural hazard occurs, they might ignore official advice that would make them less vulnerable
    • Increased vulnerability and reduced resilience may be caused by inequalities in Housing (1)
      • Populations living in informal settlements made from low-grade materials are at greater risks in a natural hazard event. These buildings might not follow building codes, so they are more likely to be unsafe. This means that homes and businesses are less likely to be able to withstand a hazard, putting lives and livelihoods at greater risk
    • Increased vulnerability and reduced resilience may be caused by inequalities in Housing (2)
      • After a natural disaster, populations from low-income groups do not always have the means to rebuild. People may still be living in substandard or temporary housing when the next natural hazard occurs 
      • Lower-income groups are more likely to live in areas that have a higher level of exposure to hazards
    • Increased vulnerability and reduced resilience may be caused by inequalities in Health care (1)
      • Populations with poor access to health care are at greater risk of illness, disease and death after a natural hazard. This may be due to:
      1. A limited number of healthcare facilities
      2. Fewer trained medical personnel 
      3. A lack of medical materials or drugs 
      • Populations with poor healthcare systems may not have hazard emergency response teams
    • Increased vulnerability and reduced resilience may be caused by inequalities in Health care (2)
      • Populations from lower income groups are also more likely to be undernourished or suffering from lower levels of immunity to disease before a natural hazard occurs, si they have increased vulnerability when that event happens 
    • Increased vulnerability and reduced resilience may be caused by inequalities in Income (1)
      • Populations with a majority of people in lower income groups are more likely to suffer in a disaster as they may lack the means to protect themselves. E.g. they may not be able to afford simple items (such as those you would find in an emergency kit) that would keep them alive until help arrives
    • Increased vulnerability and reduced resilience may be caused by inequalities in Income (2)
      • In the aftermath of a natural disaster, people from lower income groups are unlikely to have savings that will allow them to rebuild their homes and lives. If workplaces are destroyed people from lower income groups are more likely to lose the ability to earn an income as they have no means of employment 
      • The places or work of those in higher income brackets are more likely to have insurance measures in place that will protect the salaries of their employees 
    • Governance:
      • the systems of control that run a region or country
    • At both local and national governance has a part to play in how communities are able to react to natural hazards
      • A key aspect of this governance is having mitigation measures (a way of being prepared for natural hazards) in place
      • E.g. widespread educational programs for citizens and operational systems (such as flood defences) to deal with different eventualities
      • At a more basic level, governance needs to ensure that it is meeting the needs of its citizens and giving them the means to make themselves less vulnerable
      • E.g. a healthy and literate population is better equipped to cope with a disaster 
      • Government agencies are also responsible for a degree of environmental management that can reduce the likelihood of secondary hazards occurring
      • E.g. programmes that afforest bare slopes can be put in place to reduce the likelihood of landslides during and after an earthquake
      • Some countries have national disaster management agencies. These work in the immediate aftermath of a disaster to try and reduce secondary impacts and to support people most in need
      • E.g. in 2022, FEMA in the USA had an annual budget of over $29 billion, which it can use to aid regions once a states governor has declared a state of emergency
    • Local authorities are likely to have their own natural disaster action plan. This will be location specific, taking into account the particulars of a local population and the facilities available to it. If a natural disaster happens, it is local authorities who are best placed to coordinate emergency response teams and aid that may come in from other regions 
    • Population density can influence a community's vulnerability and resilience (1) 
      • In some urban areas, infrastructure systems such as a sewerage network may come under pressure in normal conditions. A natural disaster may cause part of the system to shut down, decreasing its overall capacity to cope even further 
      • Rapid levels of urbanisation mean that more people live in informal settlements which are more vulnerable to hazards
    • Population density can influence a community's vulnerability and resilience (2)
      • Urban areas have greater access to food, shelter and medical interventions that can aid a populations disaster recovery 
      • Urban areas often have larger and more vulnerable building structures which are likely to be damaged by the natural disaster
    • Isolation and accessibility can influence a community’s vulnerability and resilience (1)
      • Populations in rural or isolated areas are more vulnerable to natural disasters because it can be difficult for rescue operations teams to reach people in the immediate aftermath 
    • Isolation and accessibility can influence a community’s vulnerability and resilience (2)
      • Roads and bridges are more likely to be poorly maintained in these areas. This means these populations can suffer for longer without aid and response teams 
      • Isolated areas may also suffer from a lack of communication infrastructure, e.g. it may be difficult to summon help if there is no mobile phone services
    • Degree of urbanisation can influence a community’s vulnerability and resilience 
      • Places with a higher population density are more vulnerable to natural disasters as they are more difficult to evacuate so it's more likely people will be left behind 
      • In more densely populated areas, emergency services and facilities, such as hospitals and health clinics, are often under pressure due to the amount of people they need to cater for, This pressure increases after a natural disaster, as the need for medical facilities and emergency services is likely to increase
    • Trends in death (Social impacts)
      • When characteristics of tectonic hazards are comparable (e.g. same magnitude) it is clear that developing and emerging countries have higher losses of life than developed countries
      • For example the Haiti 2010 earthquake killed 300,000 while in the New Zealand 2011 earthquake 181 died
      • Emerging countries  (e.g. India and China) have rapidly growing cities, which increases risk due to denser populations and uncertainties over building codes and land use zoning. Corruption in government departments may also reduce the effectiveness of mitigation measures
    • Trends in costs (economic impact) (1)
      • When the characteristics of a tectonic hazard are comparable (e.g. same spatial extent), it is clear that developed countries have greater costs of damage than emerging countries 
      • This is because the ‘richer’ countries have more expensive buildings, infrastructure and technology to be damaged and high insurance costs after a disaster
    • Trends in costs (economic impact) (2)
      • Developing countries may only have significant construction in urban areas, and if rural areas are affected by a hazard, costs will tend to be low.
      • For example, volcanic eruption in Montserrat (1995) caused about $120 million damage while Mt St Helens, USA (1980), caused $970 million 
      • GDP per capita Montserrat 1990 $6,980 and USA 1980 was $12,575
    • Magnitude is the size and intensity of a natural hazard event. It is measured using a numerical score on a scale which is often based on scientific measurements from seismic instruments 
      • This means that there are inherent disadvantages with using these scales 
      • They can oversimplify the complexity and size of the hazard 
      • Measuring a hazard based on its impact can be unfair, as a country’s economic development level has a large role to play in this 
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