Tectonics EQ2 Flashcards
(52 cards)
What is a natural hazard?
A natural hazard is a natural event that has the potential to harm people and their property. A disaster is the realisation of the hazard, i.e. harm has occurred.
UN defines it as ‘a serious disruption of the functioning of a community or a society involving widespread human, material, economic or environmental losses and impacts, which exceeds the ability of the affected community or society to cope using its own resources.
Some large insurers define it as economic losses of over $1.5 million
What is a disaster?
Defined by the United Nations Office for Disaster Risk Reduction says: a disaster can be defined as “a serious disruption of the functioning of a community or society involving widespread human, material, economic or environmental losses and impacts, which exceeds the ability of the affected community or society to cope with using its own resources.” They suggest this includes 500 or more deaths.
How can we measure a disaster?
The UN suggest this includes 500 or more deaths.
Why are volcanoes less hazardous?
This low frequency of destructive events, the slower speed of onset and greater spatial predictability, together with preparedness plans, especially the ability to evacuate, make volcanoes a relatively easier hazard to manage than earthquakes, although still with their particular difficulties.
What is a risk?
The probability of a hazardous event causing harmful consequences (loss of life, injuries damage)
What is a hazard?
Is the earthquake a volcanic event itself, including relevant secondary hazards, with consideration of the character of the event (such as magnitude, speed on offset, special extent, frequency and duration).
Why is vulnerability important?
Modifying vulnerability means increasing the resilience of a community to increase its capacity to cope. In many cases, prediction, warning, and evacuation are used to move people out of harm’s way.
How can we reduce vulnerability?
Mitigation means finding ways of being prepared for possible tectonic hazards so that their impacts can be prevented a reduced. Management policies, strategies and actions are needed by governments to minimise vulnerability and reduce disaster risk for all in the community of society. The better the strategies and organisation, the greater the capacity to reduce the risk. Individuals or communities may lack the capacity to make significant improvements on their own, better governance can help reduce vulnerability.
Why is vulnerability a priority?
The vulnerability relates to human geography characteristics, such as the location of settlements, knowledge and understanding, the ability to react, resilience, community adaptation and preparedness, and technology for warning systems and protection.
What are the differences in prediction between earthquakes and volcanoes?
The prediction of earthquakes remains elusive and Charles Richter wrote that he believed that it will never be possible. One useful predictive tool is estimating the buildup of stress and strain by using the time gaps between earthquakes; this was scientifically successful for Haiti in 2010 and Nepal in 2015. But this method still does not give the precise location or precise time of an event. Volcanoes are constantly monitored by Earth scientists and geologists, working for organisations such as the United States geological survey and the British geological survey. An estimated 500 million people are at risk from volcanic eruptions and probabilities increase because then mineral resources, tourist income, or geothermal energy attract people.
What are the categories of vulnerability?
- Physical vulnerability is when people live in hazard-prone areas in buildings that offer little protection.
- Economic vulnerability is one people risk losing their jobs, assets and money.
- Social vulnerability is when a household or community is unable to support the disadvantaged people within it, for example, political isolation exists for the poor, females, elderly and rural residents.
- Knowledge vulnerability exists when people lack educational training, and there are no warning or evacuation systems in place.
- Environmental vulnerability exist what are the areas that people are living in has increased hazard risk because of population pressure, forcing people into riskier areas.
What is the hazard risk reduction equation?
Mitigation of hazard x reduction in vulnerability/ increase capacity
What is resilience?
The ability of a community exposed to hazards to resist, absorb and recover or ‘spring back’ from the effects of a hazard - is determined by the degree to which the community has the necessary resources and is capable of organising itself both prior to and during times of need.
According to the UNISDR, the resilience of a community with respect to potential hazard events is determined by the degree to which the community has the necessary resources and is capable of organising itself both prior to and during times of need.
Why is resilience important?
- Some communities have a high capacity to cope and a high resilience. This means they can reduce the chances of a disaster occurring because:
- They have emergency evacuation, rescue and relief systems in place.
- They react by helping each other, to reduce the numbers affected by hazard-resistant design or land-use planning has reduced the numbers at risk.
- For these communities, the threshold for disaster will be higher than for ones with low coping capacity.
- Resilience is the ability of a community to cope with a hazard; some communities are better prepared than others so a hazard is less likely to become a disaster. It also includes the ability to return to normal following a disaster.
What is the PAR model?
The Pressure and Release Model is used to analyse factors which cause a population to be vulnerable to a hazard. On one side of the model we have a natural hazard itself, and on the other side different factors and processes which increase a population’s vulnerability to the hazard. This vulnerability is often rooted in social processes. These are dynamic and ever-changing and are often unrelated to the hazard itself e.g. poverty, or poor governance.
Suggests what should be tackled in order to reduce the level of risk of disaster, such as root causes, dynamic pressures and unsafe living conditions. It’s based on the idea that a disaster happens when two opposing forces interact.
What is the structure of the PAR model?
The PAR model is complex; no two hazards are the same and factors leading to vulnerability are interconnected and hard to measure. If we reduce the social factors affecting a population, we can reduce the pressure they face and so reduce their vulnerability and the effect of natural hazards. The progression of vulnerability is split into three sections. The root causes are often caused by economic, demographic and/or political processes, often affecting large populations or entire countries. Dynamic pressures are local economic or political factors, that can affect a community or organisation and unsafe conditions are the physical conditions that affect an individual (unsafe building, low income, poor health, etc).
What is and what are the common root causes of the PAR model?
Vulnerability is a process that starts with root causes. These are political and economic systems that control who has power in society and who has access to resources such as money.
- Weak Governance
- Mismanagement by
Industry, NGOs or IGOs - High reliance on products
easily affected by hazards
(local agriculture near to
the hazard, imports by air
during a volcanic eruption)
What is and what are some dynamic pressures of the PAR model?
Through a series of dynamic pressures, these root causes can lead to unsafe conditions. For example, a country that is poor will probably not spend time or money enforcing building codes, which means that buildings may be poorly built. This process from root causes to unsafe conditions- is called the progression of vulnerability.
- Lack of training/knowledge in locals.
- Rapid urbanisation
- Poor communication between the government and locals
- Natural environment
What is and what are some unsafe conditions of the PAR model?
A lack of infrastructure (such as poor sewage management or water supplies) can worsen the impacts of a hazard since it is harder to maintain clean living conditions and avoid the spread of disease following a disaster. A lack of infrastructure would be a factor in unsafe living conditions.
- Lack of infrastructure (clean water, sewage removal, electricity)
- Dangerous location of settlements (close to nuclear stations or the natural hazard itself)
- No warning system for locals
How does the PAR model show impacts of the Haiti earthquake?
Root causes:
- Haiti was heavily indebted to US, German and French banks. The Haitian government had to use much of its little available money for debt repayments, rather than improving the country’s infrastructure.
- 80% of the population lives below the poverty line unless then US$2 dollars a day.
- 30 to 40% of the government budget came from foreign aid.
Dynamic processes:
- There was a lack of urban planning to control where and how buildings were constructed, and where people lived.
- There was a lack of disaster preparedness and management systems.
- There was a lack of effective education systems.
- There was rapid urbanisation, which resulted in vulnerable, slum-like housing.
- There was a high population density (in the capital, Port-au-prince, it was 306 people per square kilometre)
Unsafe conditions:
- The soft soil, on which many of Haiti’s buildings were constructed, amplified the seismic waves – increasing ground shaking and damage.
- A lot of illegal housing was built in unsafe areas, such as the hill slides.
- A low GDP per capita of US$1300 meant that buildings were constructed cheaply in quickly, which often resulted in poor-quality environmental structures.
- Before the earthquake, only 39% of Haitians had access to support and 24% to sanitation.
Haiti case study impacts:
- Haiti remains one of the world’s poorest countries.
- Haiti only had one airport, several ports and a few main roads. When these were damaged, crucial aid supplies were prevented from arriving or being distributed effectively- slowing down the rescue.
- Over a quarter of government officials were killed, and key government buildings were destroyed, making the governments even less able to organise recovery and relief efforts.
- In Oct 2010, an outbreak of Cholera occurred and as of 2016, was still ongoing. A lack of medical supplies and trained healthcare workers caused the disease to spread so that by 2015, 9000 Haitians had died and 720000 had been affected.
- Killed more than 200,000 people and left more than 300 000 people injured.
- In less than a minute, over a quarter of a million (70%) homes and buildings collapsed, this included 4, 000 schools, 8 hospitals, 75 government buildings and even the presidential palace.
- The total damage of this tragedy reached an estimated total of $7.8 billion. Also, the majority of Haiti’s agricultural industries were destroyed in the earthquake, causing unemployment levels to skyrocket.
- Broken electricity cables started fires which damaged woodland areas in Haiti. There were many landslides that occurred that destroyed natural landscapes and blocked off rural areas. Important natural and human landmarks, such as the presidential palace were also destroyed. The earthquake also triggered flooding in coastal areas due to tidal waves.
Japan case study:
- 15,894 people died, 6,152 people were injured, 130,927 were displaced and 2,562 people remain missing.
- A 9m high wave flooded the plant’s generators and electrical wiring. People lost energy immediately.
- Japan spent billions of dollars building anti-tsunami defences at heights of 12 m. The tsunami washed over them, rendering them totally ineffective.
- 332,395 buildings, 2,126 roads, 56 bridges and 26 railways were destroyed or damaged. 300 hospitals were damaged and 11 were totally destroyed.
- Around 4.4 million households in North-East Japan were left without electricity.
- some coastal areas experienced land subsidence as the earthquake dropped the beachfront in some places by more than 50 cm.
- Tsunami up to 40 m high devastated entire towns and resulted in the loss of thousands of lives. This caused a lot of damage and pollution up to 6 miles inland.
- The economic cost was US$235 billion, making this the most expensive natural disaster in world history.
- The damage caused by the earthquake resulted in the meltdown of seven reactors. Radiation levels at one point were over eight times normal levels.
- A 250-mile stretch of coastline dropped by 0.6 m, allowing the tsunami to travel further inland.
- Liquefaction occurred in many of the parts of Tokyo built on reclaimed land. 1,046 buildings were damaged.
- Geologists estimate that the Pacific plate has slipped westwards by between 20 and 40 m.
China case study:
- Initial death tolls ran at 8,700 but this eventually rose to 69,000 with 18,000 people missing two months after the quake.
- 374,000 people were injured and between 5 million and 11 million people were made homeless.
- A total of 5 million buildings collapsed; including a number of schools (Juyuan middle school in Dujiangyan city collapsed killing 900 pupils).
- Other impacts included communications being brought to a halt and the cost of restoring infrastructure was put at $75 million.
- In Shifang, chemical plants collapsed killing hundreds and releasing toxic ammonia.
- Power and water supplies were cut and flooding occurred because landslides had blocked rivers.
- 4.8 million people were made homeless.
- Public infrastructure collapsed and the provision of utilities was disrupted for an extended period. The economic losses amounted to 845 billion RMB (122 billion USD).
What were the impacts of the 2004 Indian ocean tsunami?
- In some coastal villages 70% of the villagers were killed.
- In Sumatra, 1500 villages were completely destroyed.
- In Sri Lanka, more than 60% of the fishing fleet and industrial infrastructure were destroyed.
- In Thailand, the tourism industry lost about US$25 million a month, and 120,000 workers lost their jobs.
- Ecosystems such as mangroves, coral reefs, forests and some coastal wetlands were severely damaged.
- Most vegetation and topsoil were removed up to 800 m inland
- Freshwater supplies in agriculture saw you were contaminated by saltwater
The overall economic cost came to over US$10 billion
Since then, ocean floor earthquake sensors have been installed to trigger early warnings, and many local communities have been trained in evacuation and disaster response.
