why do some tectonic hazards develop into disasters? Flashcards
what is the difference between a hazard and a disaster
A natural hazard is a threat of a naturally occurring event will have a negative effect on humans. This negative effect is what we call a natural disaster. In other words, when the hazardous threat actually happens and harms humans, we call the event a natural disaster.
shown by dreggs model
what is a threshold?
a magnitude above which a disaster occurs. this threshold level could be difference in a developed vs developing country because of the different levels of resilience.
when is the impact of an event considered to be a disaster?
- 10 or more deaths
- 100 or more people affected
- US$1 million in economic losses
what can we use to understand the relationship between hazards and disasters?
risk equation
risk= hazard x vulnerability
capacity to cope
what is meant by resilience?
the ability of a community in coping with a hazard; some communities are more prepared than others so the hazard is less likely to turn into a disaster
what can a PAR model be used for?
helps understand risk in terms of vulnerability analysis in a specific hazardous situation and is also a tool that shows how disasters occur when natural hazards affect vulnerable people. it sheds light on the importance of socio-economic contexts of a hazard.
what is the structure of the PAR model?
root cause > dynamic pressures > unsafe conditions > disaster < natural hazard
root cause: e.g low access to resources, poor governance
dynamic pressures: e.g lack of education, training and investments, rapid population change, urbanisation
unsafe conditions: e.g poor construction standards and regulations, unsafe infrastructure, poverty
natural hazard: e.g earthquake, tsunami, eruption (volcano).
what is a megadisaster?
a disaster with unusually high impacts. Today, that means millions of people are affected and billions of dollars in damage over a wide area (more than one region or country).
what is an earthquakes magnitude measured using?
the moment magnitude scale (MMS)
updated version of the Richter scale
what is an earthquakes intensity measured using?
the Mercalli scale
why is the relationship between magnitude and death toll a weak one?
- some earthquakes cause serious secondary impacts, such as landslides and tsunamis
- earthquakes hitting urban areas have a greater impact than those in rural areas.
- level of development and level of preparedness affect death toll
- isolated, hard to reach places could have a higher death toll because rescue and relief take longer.
what is the magnitude of an eruption measured using?
volcanic explosive index (VEI). ranges from 0 to 8 and is a composite index combining eruption height, volume of material erupted and duration of eruption.
what is a super volcano?
one whose impacts would be felt globally because of a worldwide cooling of the earth’s climate perhaps up to 5 years.
what can tectonic events be compared using?
Hazard profiles.
what is liquefaction?
a process that occurs in waterlogged, loose sediments; earthquakes shaking ‘liquefies’ the ground, causing buildings to tilt, sink and collapse.
what are some factors that help explain the impacts of a hazard?
social: poverty, population density
economic: poor building construction, governance
environmental: time of day, geology, terrain, isolation, duration, secondary hazards
what does a lower HDI suggest in terms of tectonic impacts?
a higher death toll.
chile (2007)- HDI of 0.83, death toll of 2
Pakistan (2013)- HDI of 0.54, death toll of 825
what are some factors increasing risk of tectonic hazard and mitigating (reducing) risks of a tectonic hazard?
increased risk:
- population growth
- urbanisation and urban sprawl
- environmental degradation
- loss of community memory about hazards
- very young or old population
- ageing, inadequate infrastructure
- greater reliance on power, water and communication systems.
mitigating risk:
- warning and emergency-response systems
- economic wealth
- government disaster-assistance programmes
- insurance
- community initiatives
- scientific understanding
- hazard engineering
in areas of low HDI (bellow 0.55), vulnerability is usually high because of what reasons?
- many people lack basic needs of sufficient water and food even during ‘normal’ times.
- much housing is informally constructed with no regards for hazard resilience
- access to healthcare is poor, and diseases and illnesses are common
- education levels are lower, so hazard perception and risk awareness are low.
what is meant by an aftershock?
events that occur in the hours, days and months after the primary earthquake and can be of high magnitude.
what does governance refer to?
the process by which a country or region is run.
describe some aspects of governance and disaster vulnerability.
MEETING BASIC NEEDS: meeting demand for food and water, supplies population with health requirments meaning they’re more able to cope with the disaster.
PLANNING: land-use planning, and regulations can reduce risk of de secondary impacts like liquefaction and landslides.
ENVI MANAGEMENT: secondary hazards like liquefaction can be made worse by deforestation. monitoring this can prevent impacts
PREPAREDNESS: raising awareness through education and community preparation programmes teach people how to prepare, evacuate and act.
-CORRUPTION: increase vulnerability as funds put towards hazard management is syphoned illegally.
OPEN-NESS: government susceptible to media can increase the likelihood of awareness, preparation, planning and aid.
what are three key geographical factors that influence the impact of a hazard?
POPULATION DENSITY- highly populated areas are harder to evacuate such as Mt Vesuvius, Italy, and are likely to be hit harder by earthquakes
DEGREE OF URBANISATION- when cities are struck by major earthquakes, such as Japan or Haiti, death toll can be high because of the concentration of at-risk people
ISOLATION AND ACCESSIBILITY- often rural areas are hit less hard that urban areas by the initial impacts of a tectonic disaster, but isolation and limited access can slow relief effort. e.g the 2005 Kashmir earthquake.
what assets to urban areas have that rural areas don’t which increase resilience?
hospitals, emergency services, food stores and transport connections.
what do countries like Japan, the USA and Chile have that ensure sociak impacts are reduced?
- advanced and widespread INSURANCE, allowing people to recover from disasters- at least in the long-term
- government run PREPARATIONS such as Japan’s disaster prevention day on 1 September each year, as well as public education about risk, coping, responding and evacuating
- sophisticated MONITORING of volcanoes and, where possible, defences such as tsunami walls
- regulated local PLANNING SYSTEMS, which use land-use zoning and building codes to ensure buildings can withstand hazards and are not located in areas of unacceptable risks.
what is land-use zoning?
a planning tool used to decide what type of buildings (residential, commercial industrial or none) are allowed in a particular location.
