Natural hazards Flashcards
what is a natural hazard ?
a natural hard is a natural hazard is a natural event that has a huge SOCIAL IMPACT
eg if a land slide happened in a remote area it would not counted as a natural HAZARD
what factors effect risk?
- URBANISATION
some of the largest cities are at risk of earthquakes (Tokyo), and tropical storms (Hati) - POVERTY
deprived areas push people to live in areas of risk
eg. Venezuela shortage of housing causes people to buil on unstable slopes prone to floods and lands slides - FARMING
eg. flood plains , they deposit fertile silt so people move closer to that land and put themselves at risk. - CLIMATE CHANGE
warmer atmosphere will have more energy and more intense storms and hurricane
how are earthquakes distributed?
occurs mainly on margins of tectonic hazards where plates are moving and building up pressure . Sometimes caused by human activity eg. underground mining
how are volcanoes distributed?
like earthquakes majority are placed on a belt that follows the plate margins
constructive and destructive plate margins
what happens at a destructive plate margin?
- two plates are moving towards each other
- deep ocean trench forms SUBDUCTION when there is an oceanic crust
- if it is two continental plates there is NO subduction and the two plates collide to form a fold mountain
- friction between toe plates cause strong earthquakes
- no volcanoes as there is no magma
what happens at a conservative plate margin?
- two plates are moving past each other
- friction between the plates cause earthquakes as stresses gradually build up over many years and suddenly released
- no volcanoes as there is no magma
what happens at a constructive plate margin?
- two plates are moving apart
- causes earthquakes
- magma forces its way through to the surface and forms volcanoes (shield volcanoes)
what are the effects of an earthquake?
PRIMARY:
ground shaking, damage to buildings, roads as well as injury
SECONDARY:
tsunami and landslides
how can you measure an earthquake?
- seismometer which produces a seismograph
- the richter scale
how much did the Nepal earthquake read on the richter scale ?
7.9
what was the primary effect of the Nepal earthquake?
- 9000 killed and 20 000 injured
- 3 million homeless
- estimated cost $5 billion
what were the secondary effects of the Nepal earthquake?
- landslides and avalanches cut off roads and effected relief efforts
- avalanches on mount Everest killed 19 people 250 missing
what were the immediate response to the Nepal earthquake?
- UK, India and China sent supplies eg water, medical support and rescue teams
- half a million tents
- helicopters help access villages cut off by landslides
what were the long-term responses to the Nepal earthquake ?
- 7000 schools rebuilt
- repairs to Everest’s base camp
- roads repaired and landslides cleared
how much did the Chile earthquake measure on the richter scale?
8.8
what were the primary effect of the Chile earthquake?
- 500 killed 12 000 injured
- 220 000 homes destroyed 53 ports and 56 hospitals destroyed
- estimated cost $30 billion
what were the secondary effects of the Chile earthquake?
- tsunamis devastated coastal towns as well as many pacific countries
- 1500 km of road damaged
what were the immediate responses to the Chile earthquake?
- power and water restored to 90% of homes within 10 days
- national appeal raised $60 million
- temporary repairs to highway within 24 hours
what were the long-term responses to the Chile earthquake?
- a month after the earthquake Chile’s government launched the reconstruction of 200 000 homes
- chile has a strong economy and did not need much foreign aid
why do people still live in areas at risk of tectonic hazard?
- some are not aware of the risk
- more effective monitoring allow people to receive sufficient warnings before earthquakes and tsunamis hit
- people living in poverty prioritise they’re basic needs
- a lot of plate margins bring benefits eg. fertile land or water
what is monitoring?
using scientific equipment to detect warning signs of events such as a volcanic eruption
what is prediction?
using historical evidence (and monitoring) to predict tectonic hazards
what is protection ?
designing buildings that can withstand tectonic hazards
what is planning?
identifying and avoiding places most at risk
what is global atmospheric circulation?
- at the equator the sun is most focused so temperature is high
- water evaporates and air rises and cools
- the water condenses and forms clouds
- moves to the tropics
where do tropical storms form?
- over warm water 27 degrees
- summer and autumn when the sea is the warmest
- 5-15 degrees of the equator
how do tropical storms form?
- upwards movement of air draws water vapour up
- evaporated water cools and condenses
- air condensing releases heat and causes more water to draw up
- several small thunderstorms join together to form giant spinning storm
- storm develops an eye and at the centre air descends quickly
- the eyewall has the most intense weather conditions
- the storm is carried across the strength and gathers strength
- when it reaches land its energy source is cut off , friction with lang slows it down and weakens it .
what were the primary effect of typhoon Haiyan ?
- 6300 people killed
- 40 000 homes destroyed
- 90% of Tacloban destroyed
- 30 000 fishing boats destroyed
- widespread flooding
what were the secondary effects of typhoon Haiyan?
- 14 million effected
- flooding caused landslides
- shortage of food, water and shelter lead to outbreak of disease
- looting and violence broke out
- many jobs were lost
what were the immediate responses to typhoon Haiyan?
- 1200 evacuated
- international aid, sent supplies and set up field hospitals
- Philippines red cross delivered basic food
what were the long-term responses to typhoon Haiyan?
- rebuilding infrastructure
- rice farming and fishing was quickly re-established
- 1000’s of homes were re-built away from areas at risk of flooding
how is tropical storms effected by global warming?
over last few decades the sea surface temperature has increased
in the future the hazard zone could increase
how can protection help against a tropical storm?
- reinforced windows and roof
- sea walls
- houses built on stilts so water can pass beneath them
- storm drains to drain excess water and prevent
flooding
what are two other ways to reduce the effects of tropical storms?
- MONITORING/PREDICTION
help evacuate people at risk before the event - PLANNING
warning people
what caused the Somerset flood?
- wettest January since records began in 1910
- high tides and storm surges swept up water from the river
- rivers hadn’t dredged for at least 20 years
what were the social impacts of the Somerset floods?
- 600 houses flooded
- cut off villages
- power outages
what were the economic impacts of the Somerset floods?
- estimated damage £10 million
- 14000 ha of agricultural ;and under water
what were the environmental impacts of Somerset floods ?
- floodwaters were heavily contaminated with sewage and other pollutants ( oil + chemicals)
- debris
- stagnant water had to re-oxygenated before being pumped back into the river
what evidence is there that weather is becoming more extreme ?
although there has always been extreme cases of weather it has been slowly getting worse and more frequent eg. floods and heavy snow
- scientist believe this is occurring due to the increasing amount of energy in our atmosphere
what is a natural cause of climate change?
- volcanic activity
- change in earths orbit
what are some human causes for climate change ?
- burning fossil fuels
- deforestation
what is carbon carbon capture ?
uses technology to capture carbon dioxide produced from fossil fuels and industrial processes which would have entered the atmosphere
what is a simple environmental way in which can manage climate change ?
PLANTING TREES
- remove carbon dioxide
- release moisture which has a cooling effect
how can we adapt to climate change ?
- irrigation systems
- managing water supply
- sea walls
