disaster risk management 3.1-3.2

Steps of disaster risk management:

1. Prevent disaster risks before the occurrence of tectonic hazards: e.g. designing hazard-resistant buildings to ensure structures can withstand hazards without collapsing easily

2. Reduce disaster risks as it occurs: tsunami and earthquake early monitoring systems -> timely evacuation and reduces loss of lives

3. Manage after the occurrence: insurance coverage which offers financial payouts to rebild properties which are damaged or destroyed

How do disaster risks and losses hinder development:

1. environmental consequences

2. social consequences:

- tectonic hazards e.g. tsunamis -> injuries and loss of lives -> people drown and get him by fast-moving debris carried by the waves

- people may become homeless as houses are destoryed -> forced to live in temporary housing which lacks proper sanitation -> poor standards of living

- sewater brought inland by the trsunami may contaminate wells and other sources of drinking water -> water pollution -> spread of diseases (e.g. cholera)

- inidividuals may suffer from physcological trauma from the loss of their homes or loved ones. In addition, the constant fear of losing their lives/ being harmed while living in these areas-> affect their mental well-being

3) economic consequences:

- destruction to homes and properties

- individuals may suffer financially as it is costly to rebuilt or reoair damaged homes

- business owners can lose incomes caused by damage to their properties

- govt needs to spend money to rebuild and repair because of damages

Why is it important to reduce disaster risk?

- for disaster-prone developing countries because:

1. social, economic, environmental consequences can be very severe -> hinder development

2. often disproportionately affected -> lack the capacity to adequately prevent, reduce and manage

- some manage to do so through research and planning:

1. cost-effective investment -> prevents future losses-> sustainable development

2. additional investments SMALL as compared to costs incurred from disaster

3. With less losse, the money to rebuild will be minimised and development gains achieved will not be lost

Earthquakes factors: nature of hazard

1. Duration of shaking:

- Duration of shaking: the length of time of ground shaking

- longer the shaking, more damaging the earthquake -> strucutures are subjected to a longer period of stress and are more likely to collapse; people will more likely be trapped in collapsed infrastrucure, leading to more deaths and injuries

2. Time of shaking:

- Time of day influences the activities carried out by people and how they respond when the earthquake strikes

- If people are asleep at night, theyh will be less alert and are unable to evacuate quickly

- On the other hand, as people are at work or school during the day, they will be more alert and will evcuate quickly -> less likely to get trapped -> less death and injuries

Earthquakes factors: vulnerable conditions

1. Quality of building design and construction:

- the poorer the quality of the building design and construction, the more vulnerable the buildings are to collapse -> more people getting trapped, injuries and loss of lives

- vulenrable to collapsing when:

1) poorly built wiht low-quality building materials e.g. zinc sheets and other rigid materials that are unable to withstand shaking

2) do not follow building codes set by authorities

3) lack earthquale-resistant features such as reinforced steel walls

2. Soil and rock properties:

- potentially open the area up to earthquake hazards like liquefaction when soil is saturated and loose:

1) buildings are more likely to sink in to the liquefied soil and tip over

2) people are more likely to get trapped under the collapsed buldings -> deaths and inuries - the softer the soil, the higher the risks - as seismic waves travel from hard rock to soft soil, the waves get amplified:

1) passing from rock to soil the waves slow down but become bigger

Earthquakes: exposure

1. population density:

- def: number of pep[le per unit of area (square kilometre km^2)

- higher the population density, the greater the number of people exposed to the earthquake: when a large number of people are located within buildings, more people will be trapped when the buildings collapse, causing more injuries and loss of lives

2. distance from epicentre:

- when the city is nearer to the epicentre, less energy is absorbed byt he rocks before the seismic waves reach the city

- as a result, the buildings and bridges are more likely to collapse and people are more likely to be trapped, leading to more injuries and loss of lives

Volcanic eruption: nature of hazard

1. Viscosity of magma:

- Low silica: less

- High silica: more

2. Nature of eruption

- Low silica: gentle, effusive eruption

- High silica: explosive eruption

3. Nature of hazards:

- Low silica: lava can flow far from the volcano before cooling and solidifying -> damage properties and infrastructure over large areas within the geographic region of the volcano

- High silica: may form highly destructive pyroclastic flows, causing widespread damage to infrastructure, injuries and loss of lives; explosion of volcanic materials may strike people and properties, resulting in more injuries and loss of lives

Volcanic eruption: vulnerable conditions

1) availability of surface and groundwater

- the greater the availability of surface and groundwater, the more likely lahars can develop

- increases vulnetability of people and properties, increasing disaster risks as lahars can bury and destroy properties, increasing likelihood of injuries and loss of lives

- large quanities of water may come from a range of sources:

1) rapid melting of snow and ice on the volcano's summit just before the eruption

2) existing lakes and rivers nearby

3) heavy rainfall

4) groundwater released through cracks and fractures during an eruption