tectonics paper 3 Flashcards
1.4a Definition of a natural hazard and a disaster, the importance of vulnerability and a community’s threshold for resilience, the hazard risk equation.
A natural hazard is a natural events 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
disasters have to involve people and they occur at the intersection of people and hazards as shown by the Degg Model:
This shows the intersection between a hazardous natural event, such as an earthquake, hurricane or landslide and a vulnerable population which experiences human and/or economic loss, to create a disaster.
disaster classed as - 10+ deaths, 100+ people affected, $1 million economic loss
The relationship between risks, hazards and people is complex, due to:
unpredictability of hazard’s timing and magnitude, catching people out
lack of alternatives - people staying due to a lack of options (work, lack of space, skills or knowledge)
dynamic hazards - threats change over time and can be affected by human influence
cost-benefit
‘Russian roulette reaction’ - fatalism, acceptance of risks whatever you do
The relationship between hazards and disasters can be understood using the hazard risk equation. The risk of disaster rises if the hazard magnitude rises (e.g. VEI 6 eruption compared with a VEI 3). If vulnerability rises (poverty, lack of preparedness, lack of awareness of potential hazards,) so does risk;
risk = (hazard x vulnerability)/capacity to cope
Resilience
Some communities have a high capacity to cope and a high resilience. This means they can reduce the chances of disaster occurring because:
they have emergency evacuation, rescue and relief systems in place
they react by helping each other, to reduce numbers affected
hazard-resistant design or land-use planning have 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.
Age affects resilience as children and old people suffer more. Around 66% of those over 60 live in less-developed regions, expected to rise to 79% by 2050.
The Disaster Risk and Age Index, compiled by the UNISDR highlights the trends of ageing populations and the acceleration of risk in a world that is increasingly exposed to a range of hazard types. It signals how age should be an important factor in understanding vulnerability and the coping capacity of older generations.
Myanmar VS Japan
1.4b The Pressure and Release Model (PAR) and the complex inter-relationships between the hazard and its wider context.
Some disasters are truly catastrophic in terms of their impact, for example the 2010 Port-au-Prince earthquake in Haiti. Its magnitude of 7.0 was relatively low, but it is estimated that 160,000 people died. The PAR model can be used to help understand this.
The PAR model suggests that the socio-economic context of a hazard is important. In poor, badly governed (root causes) places with rapid change and low capacity (dynamic pressures) and low coping capacity (unsafe conditions), disasters are likely.
It show how root causes, dynamic pressures and unsafe conditions combine with a natural hazard to create a disaster.
e.g Haiti:
Root causes:
Per capita GDP (PPP) US $1200
50% of the population is under 20 years old
Dynamic pressures:
Lack of education, training and investment
Rapid population change and urbanisation
Unsafe conditions:
25% of people live in extreme poverty
80% of Port-au-Prince’s housing is unplanned, informal slums
1.7c The concept of a multiple-hazard zone, and how linked hydrometeorological hazards sometimes contribute to a tectonic disaster. (Philippines)
Multiple hazard zones are places where two or more natural hazards occur, and in some cases interact to produce complex disasters.
e.g California, Indonesia and Japan, Philippines
These locations:
are tectonically active and so earthquakes (and often eruptions) are common
are geologically young with unstable mountain zones prone to landslides
are often on major storm tracks either in the mid-latitudes or on tropical cyclone tracks
may suffer from global climate perturbations such as El Niño and La Niña
A multiple hazard zone with complex hazards is a combination of tectonic hazards and hydro-meteorological hazards.
Tectonic hazards: earthquakes, volcanic eruptions, tsunami, landslides
Hydro-meteorological: flood, drought, storms, tropical cyclones
during the 1991 eruption of Mount Pinatubo in the Philippines the area was struck by Typhoon Yunga. Heavy rainfall from the typhoon mobilised volcanic ash into destructive lahars. This shows how linked hydrometeorological hazards can contribute to tectonic disasters.
This eruption could have been significantly worse in terms of impact, but it was successfully predicted and evacuation limited the death toll to about 850. In many earthquake-prone areas, landslides can be triggered by heavy rain on slopes previously weakened by earthquake tremors.
