natural hazards Flashcards
what is a hazard
something that poses risk to people and the environment
what is a natural hazard
a natural event which poses risks to people and the environment
what is natural
naturally occurring, not caused by people
4 types of hazards
geological
biological
meteorological
hydrological
examples of geological hazards
earthquakes, landslides, tsunamis and volcanoes
examples of biological hazards
disease epidemics and insect/animal plagues
e.g. covid-19
examples of meteorological hazards
tropical storms, droughts, wildfires and extreme temperatures
examples of hydrological hazards
avalanches and floods
what is a hazard risk
chance or probability of being affected by a natural event
5 things that increase hazard risk
location in the world
economic development
urbanisation
time of event
climate change
examples of hazard risk
people who live in low lying areas are more at risk from flooding
people who live in coastal regions are more at risk of tropical storms
people who live in urban areas are more at risk from earthquakes
if an earthquake happens during rush hour, more people will be affected
people living in LICs are less able to prepare for natural hazards like earthquakes
why can HICs cope with natural hazards better
HICs tend to be better prepared for natural hazards because they can afford good equipment to monitor, predict and evacuate areas at risk
how does earthquake on destructive plate boundary affect more people
if an earthquake at a destructive plate boundary causes a tsunami, more people will be impacted
what is the crust
above mantle
earths hard outer shell
surface we’re living on
thin- 4-7 miles deep
what is the mantle
layer above the outer core
1800 miles thick
makes up 80% of the earths total volume
what is the outer core
hot —> temps reaching 3700 degrees
1370 miles thick
what is the inner core
centre of earth that’s solid (iron and nickel)
780 miles thick
describe continental crust
land on top of it
less dense (lighter)
thick
e.g. north american plate
describe oceanic crust
ocean on top of it
heavy and dense
thinner
e.g. pacific plate
what is a convection
heat rises and falls inside the mantle which creates convection currents generated by radioactive decay
the convection currents move the plates
what is a ridge push
when plates move apart (constructive boundary), the magma rises from the mantle
magma cools and creates new, hot and dense rock
it pushes the old rock out of the way
this creates a ridge in the crust
what is a slab pull
gravity pulls the old rock into the mantle because the rock has become colder and denser
what is a constructive margin
2 plates move apart, magma rises up to fill the gap —> causes volcanoes at this type of boundary
however, since the magma can espace easily at the surface, the volcano does not erupt with much force
earthquakes are also found at constructive boundaries e.g. mid atlantic ridge
what hazards are found at constructive plate boundaries
earthquakes and volcanoes
what is a destructive plate boundary
plates move towards each other and 1 is subducted under the other
found where a continental plate meets an oceanic plate
oceanic plate descends under the continental plate because it is denser
as plate descends, it starts to melt due to friction caused by the movement between plates
melted plate is now hot, liquid rock (magma) —> it rises through gaps in the continental plate and if it reaches the surface, the liquid rock forms a volcano
example of destructive plate margin
andes mountains in south america
what is it called if subduction does not take place
collision boundary
what hazards are found on the destructive plate boundary
earthquakes, tsunamis and volcanos
what is a conservative margin
plates slide past each other
example of conservative margin
san andreas fault in california
what hazards are found along the conservative margin
earthquakes
what are primary effects
occur immediately as a result of the earthquake itself
e.g. buildings collapsing, death and injury
what are secondary effects
occur hours to days after the initial earthquake
happen due to primary effects
e.g. disease due to lack of medical facilities
HIC tectonic hazard case study
christchurch, new zealand
where is christchurch located
new zealand
in Oceania
on the conservative boundary between indo-australian plate and pacific plate
what happened in christchurch and when
22nd february 2011 at 12:51pm
magnitude 6.3 on richter scale
shaking that lasted 12 seconds
what are the primary effects (social)
people may be killed or injured
homes destroyed
transport links disrupted
water pipes may burst and water supplies may be contaminated
primary economic effects of natural hazards
shops and businesses destroyed
damage to transport can make trade difficult
primary environmental impacts of natural hazards
landscape may be destroyed
fires can spread due to gas pipe explosions —> damage areas of woodland
secondary social effects of natural hazards
disease may spread
people have to be rehoused
secondary economic effects of natural hazards
cost of rebuilding infrastructure is high
investment may only be focused on repairing the damage caused by the earthquake
income could be lost —> buildings collapsing —> business can’t happen
secondary environmental effects of natural hazards
important human landmarks may be lost —> less tourism —> less money
primary effects of earthquake in christchurch
181 people killed
200 injured
50% of central city’s buildings were damaged
80% of the city was without power
secondary effects of earthquake in christchurch
businesses were put out of action for long periods —> losses of income and jobs
couldn’t host rugby world cup so lost benefits e.g. tourism and income that they would bring
flooding from liquefaction —> difficult for emergency services to get around
immediate responses to christchurch earthquake
ordinary people helped those who were trapped
canterbury art gallery which was earthquake proof was turned into an emergency response centre
chemical toilets were provided for 30000 residents
full emergency response plan within 2 hours
long term responses to christchurch earthquake
provided temporary housing
roads and houses were cleared of silt from liquefaction by august
80% of roads were repaired
LIC case study earthquake
haiti, port au prince
where is haiti located
western hemisphere
north america
dominican republic neighbourhoods it
what happened in haiti and why and when
7.0 magnitude earthquake
12th january 2010
on conservative plate boundary —> north american plate + caribbean plate
epicentre of earthquake was about 10 miles south west of capital, port au prince
immediate responses of haiti earthquake
dominican red cross sent medical supplies
dominican emergency team assisted more than 2000 injured
twitter + facebook spread messages to help
39 trucks carrying canned food were displaced, 10 mobile kitchens and 110 cooks capable of producing 100,000 meals a day
long term responses haiti
haiti received $1 billion in aid
world bank stopped debt repayments for 5 years
dominican republic which neighbourhoods haiti offered support and accepted some refugees
primary effects of haiti earthquake
300 000 people injured
220 000 people were killed
100 000 homes were destroyed
8 hospitals in port au prince were badly damaged or collapsed
roads were blocked by fallen buildings and smashed vehicles
secondary effects of haiti
-looting became a serious problem as 2 million people were left without food or water
-1.3 million people were homeless
-haitian tourist industry declined as tourists stopped visiting
-by november 2010 there were outbreaks of cholera —> water became contaminated so chlorea spread
why do people continue to live in areas at risk from a tectonic hazard (volcanoes)
volcanic soil is extremely nutrient rich —> perfect soil for growing crops e.g. hawaii
granite is formed through volcanic activity —> very durable building material and is also very valuable
geothermal heat —> generate electricity —> cheap and environmentally friendly
lower housing prices near active volcanos
diamonds and precious materials —> lava from deep within earth contains minerals which can be mined when lava has cooled e.g. gold and silver
tourism —> creates many jobs for local people e.g. hotels, restaurants and tour guides e.g. blue lagoon
why do people continue to live in areas at risk from earthquakes
don’t happen very often —> not seen as a great threat
better building design can withstand earthquakes —> make people feel less at risk
people living in poverty may focus on other issues like food
some people may not be aware of the risks of living close to a plate margin
why are risks of hazards greater is LICs than in HICs
-preparation in HICs are usually better than in LICs —> constant drills and practices so they know what to do in an emergency e.g. japan, all schools have frequent earthquake drills where people hide under tables and practise evacuating
-housing is usually poor quality in LICs
Describe what is meant by ‘monitoring’ tectonic hazards?
Using scientific equipment to detect warning signs of events
prediction?
Using evidence and monitoring information to make a judgement about when
an earthquake or volcano is likely to happen.
protection?
Designing buildings to withstand tectonic hazards
planning?
Identifying places at risk of tectonic hazards and ensuring people know what to do in the event of an earthquake/volcano.
examples of monitoring
Volcanoes
• satellites detect changes in volcano shape
• increasing amounts of gases such as carbon dioxide and hydrogen sulfide is
given off before an eruption
Earthquakes
• there is no reliable way of monitoring and predicting earthquakes.
examples of prediction
Volcanoes & Earthquakes
• It is incredibly difficult to accurately predict an earthquake or volcanic eruption
examples of planning
Volcanoes & Earthquakes
• Identify areas at risk and don’t build on these areas
• Plan open areas outside buildings where people can assemble during an evacuation
examples of protection
Volcanoes
• Divert lava away from built up areas by using explosives
Earthquakes
• Reinforced foundations
• Shock absorbers to absorb ground shaking
• Automatic shutters to cover windows preventing shattering glass
epicentre?
point on earths surface directly above the focus
seismic waves
vibrations or waves of energy released by an earthquake
focus
origin of the earthquake
facts about haiti
most houses are self built with no foundations or rules restricting height —> many built on steep hillsides
poorest country in the western hemisphere
66% earn less than £1 a day
comparison LIC and HIC
why do storms have severe effects
-wealth of country and money invested in forecasting, warning systems, protection, planning and responses
-living in coastal zone
-quality of infrastructure and building design
-strength of coastal defence
