paper 1, section a, challenge of natural hazards Flashcards
what are natural hazards?
a natural event that has a social impact
what are geological/tectonic hazards?
an extreme natural event in the crust of the earth that pose a threat to life and property
what are atmospheric hazards?
they occur as a result of processes in the atmosphere
what are some examples of atmospheric hazards?
- rain
- lightning
- drought
- snow
- hurricanes
- tornadoes
- wind
what category does flooding fall under?
not atmospheric or geological - hydrological
what are some examples of geological hazards?
- volcanoes
- landslides
- mudflows
- avalanches
- earthquakes
what factors affect risk?
- urbanisation
- poverty
- climate change
- farming
how does poverty affect risk?
poverty may force people to live in areas at risk
e.g. in Lima in Peru or Caracas in Venezuela there is a shortage of housing means people have had to build on unstable slopes prone to floods and landslides
how does climate change affect risk?
in a warmer world the atmosphere will have more energy leading to more intense storms
e.g. places may become wetter with an increased risk of flooding or drier and prone to droughts and famines
what are the two types of tectonic plates?
oceanic plate/crust
continental plate/crust
how are the two types of plates different?
oceanic plates are thinner and denser whereas continental plates are thicker and less dense
what mechanisms drive plate movement?
- they move due to convection currents which are currents of heat
- gravitational sliding which includes two mechanisms
what are the two mechanisms of gravitational sliding?
ridge push and slab pull
what is ridge push?
it happens at constructive plates; two plates are pushed apart by the injection of new magma
what is slab pull?
it happens at destructive margins where gravity acts upon the thicker, denser plate = sinks under its own weight
what happens at destructive/convergent plate boundaries?
- where the plates meet, a deep ocean trench is formed
- the dense oceanic plate subducts below the less dense continental plate
- friction between the plates creates strong earthquakes
- the subducted oceanic plate melts, creating less fluid magma (high viscosity)
- eruptions from the steep-sided composite volcanoes are often violent and explosive
what happens at constructive/divergent plate boundaries?
- magma forces its way up to the surface
- when the magma breaks through the crust it can cause small earthquakes
- upon reaching the surface it forms volcanoes
- the magma is hot and fluid (low viscosity) and results in broad, flat shield volcanoes
what happens at conservative/transform plate boundaries?
- friction between these plates causes earthquakes
- earthquakes happen as stresses build up gradually over many years
- they can be very destructive as they occur near the earth’s surface
- there are no active volcanoes at this tectonic plate margin
when and where did the earthquake occur in Nepal?
April 2015, in Gorkha
when and where did the earthquake occur in Italy?
April 2009, in L’Aquila
what was the magnitude of of the earthquake in Nepal?
7.8
what was the magnitude of of the earthquake in Italy?
6.3
how many deaths occurred due to the earthquake in Nepal?
8,841 (19 on Mount Everest)
how many deaths occurred due to the earthquake in Italy?
308
how many people were made homeless by the earthquake in Nepal?
1 million
how many people were made homeless by the earthquake in Italy?
67,500
what was the cost of damage of the earthquake in Nepal?
US $5.15 billion
what was the cost of damage of the earthquake in Italy?
US $1.1 billion
what were the primary effects of the earthquake in Nepal?
- 8,841 dead
- over 16,800 injured
- 1 million homeless
- 26 hospitals and 50% of schools were destroyed
what were the secondary effects of the earthquake in Nepal?
- started an avalanche on Mount Everest which impacted Everest Base Camp and therefore affected tourism
- earthquake occurred right before monsoon season which is when rice is planted; rice is Nepal’s ‘staple diet’ and since 2/3 of the population rely on farming, it’s very important; rice seed which was stored in homes was destroyed which caused food shortages and loss of income
- in 2014, tourism was reported to be 8.9% of Nepal’s GDP and was expected to increase by 5.8% in 2015; however, until Nepal recovers from the earthquake, tourism, employment and income will shrink
what were the short-term responses for the earthquake in Nepal?
- temporary shelters were set up: the Red Cross gave out tents for 225,000 people
- the UK’s disasters emergency committee and the US raised US $126 million by September 2015 for emergency aid and to help begin to rebuild the worst-affected areas
- several companies did not charge for phone calls
what were the long-term responses for the earthquake in Nepal?
- Nepal’s government (as well as the UN, EU etc) carried out a post-disaster needs assessment and found 23 areas required rebuilding e.g. housing, schools, agriculture etc
- the durbar square heritage sites reopened in June 2015 and Mount Everest reopened for tourists by August 2015
- six months later, the FAO started a recovery phase; people were trained how to repair and maintain irrigation systems damaged by landslides from the earthquake to help crop production
what were the primary effects of the earthquake in Italy?
- est. 308 people killed
- 1,500 injured
- 67,500 homeless
- approx. 10,000-15,000 buildings collapsed e.g. churches, San Salvatore hospital, National Museum etc
what were the secondary effects of the earthquake in Italy?
- aftershocks set off landslides and rockfalls which damaged transport and houses
- the amount of students at L’Aquila university decreased
- a lack of housing caused rent and house prices to increase
what were the short-term responses for the earthquake in Italy?
- 40,000 tents given out and shelter for 10,000 provided in hotels
- British Red Cross raised £171,000 to help
- Italian Red Cross searched for survivors- with seven dog units, 36 ambulances and a temporary hospital
what were the long-term responses for the earthquake in Italy?
- residents didn’t have to pay tax in 2010
- students were allowed free public transport, discounts on educational equipment and exemption from university fees for 3 years
- homes took several years to rebuild whilst historic centres were estimated to take 15
why do people choose to live in hazardous areas?
- earthquakes and volcanic eruptions don’t happen very often, they are not seen as a great threat in most people’s lives
- better building design can withstand earthquakes so people feel less at risk
- more effective monitoring of volcanoes and tsunami waves enable people to receive warnings and evacuate before events happen
- some people may not be aware of the risks of living close to a plate margin
what are the benefits of living on a plate margin?
- access to hot water
- dramatic landscapes which increase tourism and increase employment
- volcanic rocks (building materials)
- geothermal energy which is used to produce electricity
what is an example of where people benefit from living in a hazardous area?
Iceland
how to people in Iceland take advantage of the environment?
- hot water from within the earth’s crust provides heat and hot water for nearly 90% of all buildings in Iceland
- geothermal energy is used to generate 25% of the country’s electricity (most of the rest is generated by hydroelectric power)
- volcanic rocks are used in construction for roads and buildings
- Iceland’s dramatic landscape with waterfalls, volcanoes and mountain glaciers has become a huge draw for tourists; tourism provides jobs for many people
what are the four main management strategies?
- monitoring
- prediction
- protection
- planning
what is monitoring?
the use of scientific equipment to detect warning signs
how is monitoring used to manage the risks of volcanic eruptions?
- remote sensing (satellites)
- seismicity (seismographs)
- ground deformation (laser beams measure the ground)
how is monitoring used to manage the risks of earthquakes?
- occur without warning most of the time
- bulging of the ground
- raised groundwater levels
what is prediction?
the use of historical and scientific research to predict when and where
how is prediction used to manage the risks of volcanic eruptions?
- linked to monitoring, allows more accurate predictions and effective evacuation
how is prediction used to manage the risks of earthquakes?
- impossible due to lack of clear warning signs
- however, historical records can help determine probability and help plan for them
what is protection?
designing buildings or shelters to withstand events
how is protection used to manage the risks of volcanic eruptions?
- little can be done to protect houses, but diversions can be used for lava (embankments)
how is protection used to manage the risks of earthquakes?
- drills help keep people alert and prepared
- earthquake-resistant construction is the best way to reduce risk
what is planning?
identifying and avoiding places most at risk
how is planning used to manage the risks of volcanic eruptions and earthquakes?
- areas are mapped to assist with identifying areas to practice evacuation or restrict building