Hazard and disasters
What is Hazard ?
Hazard is a situation that poses a level of threat to life, health, property, or environment.
Key words:
Hazard: a threat (whether natural or human) that has the potential to cause loss of life, injury, property damage, socio-economic disruption or environmental degradation.
Hazard event: the occurrence (realisation) of a hazard, the effects of which change demographic, economic and/or environmental conditions.
Disaster: a major hazard event that causes widespread disruption to a community or a region, with significant demographic, economic and/or environmental losses, and which the
affected community is unable to deal with adequately without outside help.
Vulnerability: the geographic conditions that increase the susceptibility of a community to a
hazard or the impacts of a hazard event.
Risk: the probability of a hazard event causing harmful consequences (expected losses in terms of death, injuries, property damage, economy and environment.)
Hazard: a threat (whether natural or human) that has the potential to cause loss of life, injury, property damage, socio-economic disruption or environmental degradation.
Hazard event: the occurrence (realisation) of a hazard, the effects of which change demographic, economic and/or environmental conditions.
Disaster: a major hazard event that causes widespread disruption to a community or a region, with significant demographic, economic and/or environmental losses, and which the
affected community is unable to deal with adequately without outside help.
Vulnerability: the geographic conditions that increase the susceptibility of a community to a
hazard or the impacts of a hazard event.
Risk: the probability of a hazard event causing harmful consequences (expected losses in terms of death, injuries, property damage, economy and environment.)
~Characterizing hazards and disasters~
1)Magnitude: the size of the event, e.g. Force 10 on the Beaufort Scale, which measures wind speed, the maximum height or discharge of a flood, or the size of an earthquake on the Richter scale.
2)Frequency: how often an event of a certain size occurs. For example, a flood 1 metre high may occur, on average, every year. By contrast, in the same stream a flood of 2 metres in height might occur only once every 10 years. The frequency is sometimes called the recurrence interval. According to Gumbel`s laws of extremes, the larger the event, the less frequently it occurs. Earthquakes with a magnitude of over 8 occur, on average, once a year, whereas those those with a magnitude of 3 or 4 occur far more frequently.
1)Magnitude: the size of the event, e.g. Force 10 on the Beaufort Scale, which measures wind speed, the maximum height or discharge of a flood, or the size of an earthquake on the Richter scale.
2)Frequency: how often an event of a certain size occurs. For example, a flood 1 metre high may occur, on average, every year. By contrast, in the same stream a flood of 2 metres in height might occur only once every 10 years. The frequency is sometimes called the recurrence interval. According to Gumbel`s laws of extremes, the larger the event, the less frequently it occurs. Earthquakes with a magnitude of over 8 occur, on average, once a year, whereas those those with a magnitude of 3 or 4 occur far more frequently.
3)Duration: the length of time that an environmental hazard exists. This varies from a matter of hours, such as with urban smog, to decades, in the case of drought, for example.
4)Areal extent: the size of the area covered by the hazard. This can range from very small scale, such as an avalanche chute, to continental, as in the case of drought.
5)Spatial concentration: the distribution of hazards over space whether they are concentrated in certain areas ( tectonic plate boundaries, coastal locations, valleys )
6)Speed of onset: it is the time difference between the start of the event and the peak of the event. It varies from rapid events ( Kobe earthquake ) to slow timescale events ( drought in the Sahel in Africa )
7)Regularity: some hazards are regular ( tropical cyclones ) and other are more random (
earthquakes )
Vulnerability
- Vulnerability is defined as the conditions that increase the sensitivity(susceptibility) of a community to a hazard or to the impact of a hazard event. It depends on:
- Population density: Many rapidly growing cities are in hazardous areas
- Understanding of the area: Migrants into shanty towns may be unware of some of the natural hazards posed by that environment
- Public education: Educational programmes have helped people to reduce the number of deaths
- Awareness of hazards: People should be aware of any hazards that their environment is capable of
- The existence of an early-warning system: This system should inform people very early in order to react quickly and on time
- Effectiveness of lines of communication: A swift responce from the government which can mobilize people easily with allowement of overseas aid into country
- Insurance cover: The poor are most likely to be affected because they dont have insurance cover and their housing quality is very poor which will wash their houses away without paying back amends
- Construction styles and building codes: Every building needs to be built in the specific way to stand the power of the disaster in order to reduce the costs and damages
- The nature of society: The failure of the Burmese government to allow aid to the victims of Cyclone Nargis in 2008 increased the number of deaths from disease and malnutrition
- Cultural factors: The extent of trust in government, the extent and success of social networks and the amount of control or autonomy a community feels it has.
CASE STUDY: Social vulnerability and Hurricane Katrina (MEDC's)
- Katrina made landfill and it floded the streets, tore roofs and walls off historic buildings and brought down many trees
- Many homes were submerged
- Most of the city went under water
- Floods brought poisonous snakes, diseases, carcasses of livestock
- The floodwaters became 10 times more toxic
- People with cars were able to evacuate before the Katrina hit but the others were left stranded
- Rescue operation was criticized for not doing enough to help
CASE STUDY: Vulnerability to tropical storms in Haiti (LEDC's)
- Vulnerable to tropical storms and hurricanes
- The high rate of population growth and rapid urban expansion do not allow aquifers and floodplains to function as natural storage
- There is no chance of diminishing Haiti's vulnerability to severe flooding without mitigation efforts
- Earthquake (shallow and severe) about 7.0 on the Richter scale and houses that are not earthquake resistant make disaster devastating
- Prospects for reduced vulnerability to natural disasters are very limited because of poor economic development
Hazard event prediction
-They form between 5 and 30 latitude and move westward and slightly towards the poles
-As hurricane move poleward it picks up speed and reach the speed from 30 to 60 km/h
-An average hurricane can travel 4,800 km before it dies out when they leave the tropics and start moving over land
-Hurricanes occur between July and October (Atlantic, eastern and western Pacific north of the equator) and occurs between November and March (Australia and in the Indian ocean)
-Satelits detect hurricanes in their early stages of development which can help provide early warning, weather radar can locate storms within 320 km of the radar station
- Predicting a hurricane
-They form between 5 and 30 latitude and move westward and slightly towards the poles
-As hurricane move poleward it picks up speed and reach the speed from 30 to 60 km/h
-An average hurricane can travel 4,800 km before it dies out when they leave the tropics and start moving over land
-Hurricanes occur between July and October (Atlantic, eastern and western Pacific north of the equator) and occurs between November and March (Australia and in the Indian ocean)
-Satelits detect hurricanes in their early stages of development which can help provide early warning, weather radar can locate storms within 320 km of the radar station
Responces to disaster
In May 2008 an earthquake of 7.9 power on the Richter scale devastated the Chinese province. It was caused by Indian plate pushing Eurasian plate. Over 69 000 people were killed and 18 000 were missing whilst 4.8 million people were made homeless. Rivers were blocked by landslides forming quake lakes. Chinese government received praise for its swift rescue and openness to receive foreign aid.
The Burmese government received considerable criticism for the way it dealt with Cyclone Nargis. The cyclone hit Burma causing 134 000 people to die and 56 000 people missing. The financial cost of this disaster was $10 billion. However, the event was a human made disaster. Military rulers seemed unaware of the scale of the disaster and refused international aid whereas they just accepted small amount of aid after two weeks. Aid workers suggested that this response will result in a final death toll of over a million as a result of lack of clean water, food, medicine and shelter rather than the cyclone itself.
The Burmese government received considerable criticism for the way it dealt with Cyclone Nargis. The cyclone hit Burma causing 134 000 people to die and 56 000 people missing. The financial cost of this disaster was $10 billion. However, the event was a human made disaster. Military rulers seemed unaware of the scale of the disaster and refused international aid whereas they just accepted small amount of aid after two weeks. Aid workers suggested that this response will result in a final death toll of over a million as a result of lack of clean water, food, medicine and shelter rather than the cyclone itself.
Haiti's earthquake occured on 12th of January powerful of 7 degrees on the Richter scale 25 km from the Port-au-Prince causing 230 000 people to die and 250 000 people injured and a million homeless. Seven days after the earthquake the United Nations had got food supplies for only 200 000 people. Help was sent from Mexico, China, Britain, France, Germany and Canada. Red Cross was the first to join the relief effort. The World Bank led with a $100 million commitment and the UN released $10 million from its emergency fund and European countries pledged $13.7 million. Most of this aid arrived late. Haiti is the poorest country that was overpopulated and vulnerable even before the disaster. The country had only 2 fire station and no army. The earthquake degraded health service by destroying many hospitals and clinics including all 3 aid centers. Hospitals started working a month after disaster. About 550 000 people were gathered in camps which were crowded even a month after the disaster. San Francisco's earthquake was the same magnitude as the Haiti's one but it killed just 63 people. Buildings are designed to withstand the shock whereas the Haitian government has never enforced building codes. For Haiti to re build its infrastructure it was needed between $8 and $14 billion. A long term strategy to re build Haiti is vital and even before the disaster Haiti was degraded with few basic services. The country needs a strong government to put it to right and development authority needs power to act which will be the best way forward.
Adjustment and response to hazards
People cope with hazards in a number of ways and there are 3 important factors affect how a person copes:
- Experience (people with more hazard experience are better able to adjust to them)
- Levels of wealth (people with more money have more choices open to them)
- Personality (is the person a leader or a follower a risk-taker or very cautions?)
- Do nothing and accept the hazard
- Adjust to living in a hazardous environment
- Leave area
- The type of hazard
- The risk of the hazard
- The likely cost (loss) caused by the hazard
- Modyifying the hazard event through building design and location
- Improved forecasting and warning
- Sharing the cost of loss through insurance or disaster relief
Hurricane watches and warnings
A hurricane watch is issued when there is a threat of hurricane conditions within 24-36 hours. A hurricane warning is issued when hurricane conditions are expected in 24 hours or less.
During a hurricane watch
A hurricane watch is issued when there is a threat of hurricane conditions within 24-36 hours. A hurricane warning is issued when hurricane conditions are expected in 24 hours or less.
During a hurricane watch
- Listen to the radio or television for hurricane progressreports
- Check emergency supplies
- Fuel car
- Bring in outdoor objects and anchor objects that cannot be brought inside
- Secure buildings by closing and boarding up windows
- Remove outside antennas and satellite dishes
- Turn refrigerator and freezer to coldest settings, open only when neccesary and close quickly
- Store drinking water in clean bottles
- Know where you are going to shelter if the need arises