Natural hazards Flashcards
(44 cards)
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
