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Natural Hazards (tectonic bounderies (a destructive plate margin - when…
Natural Hazards
tectonic bounderies
a destructive plate margin - when the two plates collide, the oceanic plate (nazca plate) is forced underneath the continental plate ( south american plate ). this is known as subduction, this is happening because the oceanic is heavier. when the oceanic plate sinks into the mantle it melts to form magma. this pressure of the magma gets built up beneath the earth's crust. this can cause earthquakes and if the pressure is even higher can cause a violent volcanic eruption.
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constructive plate margins -the plates move apart from one another. this then causes the magma from the mantle rises up to construct new land in the form of a shield volcano. the plates movement causes earthquakes.
for example the mid-atlantic ridge- located along the floor of the Atlantic Ocean, and part of the longest mountain range in the world. for example 12 years ago there was one with a depth f 9km and a magnitude of 6.9. there are earthquakes happening every single day in the mid-atlantic ridge, as it is constantly active.
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conservative plate margins - the plates move past each other side by side at different speeds. when the plates move it creates friction and the plates become stuck. the pressure rises because they plates are still trying to move. when the pressure is finally released it releases out a huge amount of energy, causing earthquakes. these earthquakes can be very devastating as they occur really close to the earths crust, but there are no volcanoes.
for example San Andreas Fault in California- a continental transform fault that extends roughly 1,200 kilometers through California. It forms the tectonic boundary between the Pacific Plate and the North American Plate. california have around 2-3 earthquakes per year, each time this happens the fault gets gradually bigger.
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Haiti (2010)
secondary effects
- 2 million people were left without the essentials of food and water.
- power cuts occurred most days frequently.
- Crime increased - looting became a problem and sexual violence escalated.
- People moved into temporary shelters.
- By November 2010 there were outbreaks of cholera and many more disease broke out.
short term responses
- Crucial aid was slow to arrive due to the damaged port, but arrived to help all the people.
- USA sent rescue teams and 10,000 troops.
- Bottled water and purification tablets were provided by the aid charities.
- 235,000 people were moved to less-damaged cities away from Port-au-Prince.
- The UK government donated £20 million. Along will many other countries. they came together and helped support Haiti really quickly.
long term responses
- Haiti was dependent on overseas aid. as there was no aid charities on the island so it had to come from overseas, which took a few days.
- New homes were built to a higher standard although the response was slow. One year after the earthquake, over one million people were still living in temporary shelters.
- The port needed rebuilding which required a large amount of investment.
- the overall money spent to rebuild Haiti will be around US$8.1 billion and US$13.9 billion.
Haiti
12 January 2010, a 7.0 earthquake struck Haiti. The earthquake occurred on a destructive plate margin between the Caribbean and North American plates. The focus was only 12.87 km deep and the epicentre was just 25.75 km from the capital, Port-au-Prince.
primary effects
- 316,000 people were killed.
- 300,000 people were injured.
- The main port was badly damaged. Eight hospitals collapsed.
- 100,000 houses were destroyed and 200,000 were damaged.
- 1.5 million people became homeless.
managing earthquakes
Planning the location of infrastructure
- They will build away from earthquake prone areas, which can help reduce economical damage and also reduce the amount of deaths.
- For example in the USA they have a earthquake risk map, which helps control land use and also minimise damage.
- They can implement guidelines on the location of new infrastructure and set limits on the heights of buildings.
- But The control of land use is difficult in cities of developing countries where there is high rural-urban migration and the country lacks the resources to improve and help reduce the situation.
Designing Earthquake-Resistant Infrastructure
- New infrastructure can be specially designed to withstand strong tremors, which would have been tested and developed by the use of the latest technology.
- Earthquake Resistant Building have Cross-bracing which Reinforce walls using two steel beams, Shock absorbers which can absorb tremors of earthquakes, also they have concrete walls with steel bars in them to reduce rocking movements.
- One of the limitations of this is People living in LEDCs cannot afford to construct such expensive earthquake resistant infrastructure.
Strengthening Existing Infrastructure
- New infrastructure can be specially designed to withstand strong tremors and reduce damage from earthquakes.
- For example Existing infrastructure can be reinforced by wrapping steel frames around the pillars of buildings and bridges, or by placing steel rods in existing structures.
Education on Emergency Procedure
- Some Earthquake drills are conducted regularly in many earthquake-prone countries to educate and familiarise people on what to do in the event of an earthquake.
- The Governments of earthquake-prone countries also use posters and signs to warn people about areas that are prone to earthquakes and devastating damage.
- But a big problem is that People tend to be complacent and may not see the importance of earthquake education especially if earthquakes have not happened in the region for a long time.
Earthquake Monitoring and Warning Systems
- Earthquake-prone areas should invest in seismometers and computers that can monitor tremors of the Earth or change in water levels, especially the most at risk.
- After that Authorities will then inform residents through sirens or public broadcasts of impending danger and begin mass evacuation.
One of the main limitations of warning systems is that the Authorities may choose to ignore warnings to avoid disruptions to business and tourism as Predictions of scientists may not always be accurate and turn out to be false alarms.
Japan (2011)
primary effects
- Over 15,894 people died.
- Over 2,000 people are still missing.
- Made over 500,000 people homeless.
- 6,152 people were injured in the earthquake ans tsunami.
- 332,395 buildings were destroyed and demollished along with 300,000 hospitals.
- 4.4 million people around japan were left without electricity.
secondary effects
- The tsunami that followed after the earthquake caused even more damage to the port and swallowed coastal villages.
- The airport control tower was destroyed making it hard for planes to land. the airport also became a carpar as planes could land but couldn't take off.
- The earthquake caused the earth to tilt 25cm on its axis and slowed down the rotation of the earth causing the days to be shorter.
- The tsunami travelled all through hawaii travelling 5,000 miles and at 450mph and stopping in california.
the Japan earthquake was on a destructive plate margin. The earthquake was 20 times stronger and bigger, with over 10,000 aftershocks. the loss of buildings ment loss of businesses meaning no income for lots of people all over Japan. The Toyota car factory in Japan was closed down for 6 months. Also due to the nuclear melt down and the radiation thousands of people had to evacuate from there homes and become homeless in a shelter.
Response
people had a 60-second warning on their phones and TVs to give them time to brace themselves for the earthquake but also to get to higher ground from the tsunami. The emergency services also responded quickly as they were first on the scene after the earthquake to quickly try and help people out of fallen buildings. Japan managed to recover from this natural disaster by themselfs as they didnt need help from another coutry, unlike Haiti.
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