tectonic processes: natural hazards

what is a disaster?

• when a hazard has a significant impact on people

• if the damage caused by a hazard exceeds a threshold level, a disaster has happened

what is risk?

• this is the probability of a hazard happening and creating a loss of lives and livelihoods

what is vulnerability?

• this is the risk of exposure to hazards paired with an inability to cope with them

what is resilience?

• this is the degree to which a population or environment can absorb a hazardous event and stay organised and functioning

what is the hazard-risk equation?

• risk = (hazard x vulnerability)/capacity to cope

which features increase a population’s ability to cope?

• emergency evacuation systems

• rescue and relief systems

• hazard-resistant design

• land-use planning

what is the pressure and release model?

• a model showing the connections between the nature of a hazard and its wider context

• it shows how the progression of vulnerability and the natural hazard interact to cause a disaster

what are the social impacts of a hazard?

• deaths

• injury

• wider health impacts, including psychological

what are the economic impacts of a hazard?

• loss of property

• loss of businesses

• loss of infrastructure

• loss of opportunities

what are the environmental impacts of a hazard?

• damage or destruction of ecosystems

why is it difficult to compare impacts between countries?

• physical nature of events are different

• socio-economic characteristics of the place are different

• the economic costs in developed countries may be very large, but less costly in developing countries

• deaths in developed countries are usually low, but they can be higher in others

• the impacts of volcanic eruptions are smaller than the impacts of earthquakes and tsunamis

how is earthquake magnitude measured?

• the moment of magnitude scale (mms)

• this goes from 1-10

• it is logarithmic

how is earthquake damage measured?

• the mercalli scale

• usually given in roman numerals

• this is on a scale of 1 to 12

how is the magnitude of volcanoes measured?

• the volcanic explosivity index (vei)

• this takes into account the volume, duration and column height of eruptions

what are hazard profiles?

• these are profiles which summarise the physical processes shared by all hazards so that decision makers can determine which areas are most at risk

what do hazard profiles take into account?

• magnitude

• speed of onset

• areal extent

• duration

• frequency

• spatial predictability

where do high-risk events mainly occur?

• at subduction zones

• at collision zones

what is the hazard profile of kashmir, india 2005?

• high magnitude (mms 7)

• ground shaking intensity of VII (mercalli scale)

• speed of onset was rapid

• areal extent was over 1000km²

• short duration, but landslides and aftershocks lasted very long

• low spatial predictability

• low frequency

what are the root causes of hazards?

inequality of access to

• education

• housing

• healthcare

• income

how is inequality of access measured?

• HDI 

• low HDI is 0.55 and below

why do locations with a low HDI have high vulnerability?

• people lack basic things necessary for survival

• a lot of housing is informally constructed with no regard for hazard resilience

• there is poor access to healthcare so disease and illness are common

• education levels are lower so hazard perception and risk awareness are also low

• the government may not be able to provide social security or healthcare to low-income groups after a disaster

how can good governance reduce disaster vulnerability?

• if the governant can meet the day-to-day needs of its citizens, the country will be less vulnerable to disasters

• EG providing sufficient food and water for the population

• it should also be tackling corruption and ensuring aid money is not taken by officials

how can preparedness reduce disaster vulnerability?

• land-use planning and zoning to prevent house construction in dangerous areas

• environmental management to prevent factors such as deforestation making the area more dangerous

• having effective monitoring systems

• providing education and community awareness programs

• having insurance

how do population factors influence vulnerability to natural disasters?

• highly populated areas will be hard to evacuate because there are so many people

• isolated populations in inaccessible places will take a long time to reach

how can urbanisation affect vulnerability?

• the death toll can be high because of the amount of people at risk

• urban areas usually have more assets (hospitals, food stores, transport systems) than rural areas, increasing resilience