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Description
Flashcards by Annie Loizides, updated more than 1 year ago
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Created by Annie Loizides
about 7 years ago
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| Question | Answer |
| What is a natural hazard? | an event that poses potential risk to people and property. This risk is enhanced by an increasing population and technological developments which lead to faster travel. |
| Describe the pattern of earthquakes. | It is most commonly caused by a sudden movement of rocks within the Earth's crust. This occurs mainly at the margins of tectonic plates. |
| For earthquakes thta do not occur at plate margins, what are they caused by? | Human activity such as underground mining or oil extraction |
| What are the two types of crust and describe their features | Oceanic crust- dense and thin Continental - less dense and thick |
| How do plates move ? | Due to convection currents from deep within the earth. |
| What does tectonic activity at plate margins cause? | Earthquakes and volcanoes |
| Give examples of tectonic haxards | avalanche, earyhqaukes, voclanoes |
| Give examples of atmospheric hazrads. | tornadoes, hurricanes |
| give examples of geomorphological hazards. | avalanche, floods |
| give examples of biological hazrads. | forest fires |
| What is the continental drift | Plates moving apart |
| What are the types of plate boundaries | constructive, destructive, conservative and hot spots |
| Describe a constructive plate margin | -where 2 plates are moving apart -magma forces its way to the surface along the mid-atlantic ridge -as it breaks through the overlying crust, it causes earthquakes -on reaching the surface, it forms volcanoes -magma is hot and fluid -lava erupting from a volcano will flow a long way before cooling -broad and flat shield volcanoes |
| describe a destructive plate margin. | -2 plates are moving apart -where the 2 plates meet a deep ocean trench has formed -the dense plate is subducted beneeath the less dense plate -friction between the plates cause and earthquake -as the oceanic plate moves downwards it melts-creating less fluid magma -it breaks through the surface to form steep-sided composite volcanoes -eruptions are often very violent and explosive |
| What happens where 2 continental plates meet? | there is no subduction. The two plates collide and the crust becomes crumpled and uplifted. This collision forms fold mountains (Himalayas) These mountain building processes cause earthquakes. There are no volcanoes at these collision margins because there is no magma. |
| Describe a conservative plate margin? | -2 plates slide past each other -friction between the plate cause earthquakes -earthquakes happen along the conservative margins as the stresses build up. -they can be destructive as they are close to the earth's surface and are released suddenly when the plates slip and shift. -no volcanoes-no magma |
| What are hot spots? | places within the mantle where rocks melt to generate magma. The presence of a hot spot is inferred by anomalous volcanism (i.e. not at a plate boundary), such as the Hawaiian volcanoes within the Pacific Plate. |
| What are primary effects? | Caused by the ground shaking and can include deaths and injuries, and damage to roads and buildings |
| What are secondary effects? | The result of primary effects and include tsunami fires and landslides |
| Primary effects of teh Chile earthquake(27 feb 2010) | -caused by the ground shaking -around 500killed and 12 000 injured. -many homes, schools, hospitals, ports and publci buildings -port of talacahuano and santiago airport badly damaged -much of chile lost power, water and communications lost -cost estimated at US$3o billion |
| Secondary effects of the Chile earthquake | -tsunamis, fires and landslides -1500 km of roads damaged mainly by landslides -several coastal towns devastated by tsunami waves. -pacific countries struck by tsunami |
| Primary effects of the Nepal earthquakes (25th april 2015) | -9000 dead -20,000 injured -3 million left homeless -7000 schools destroyed -50% of shops destroyed, affecting food supplies -cost of damage estimated: US$5 billion |
| Secondary effects of of the Nepal earthquake | -ground shaking triggered landslides and avalanches -avalanches on Mt Everest killed about 19 people -a landslide blocked the Kali Gandaki river -teh earthquake ocurred on land so did not cause a tsunami |
| Immediate responses to Chile | -National appeal -raised Us$60 million to provide 30,000 emergency shelters -power and water restored to 90% of homes within 10 days |
| Long term responses to Chile | -Strong economy so did not need financial aid to rebuild |
| Immediate responses to Nepal | -Financial aid pledged by other countries and medical support arrived quickly from the Uk, India and China. -Social media widely used in search and rescue operations -Helicopters rescue from avalanches and delivery of supplies to remote villages cut off by landslides. |
| long-term responses to Nepal | -relied upon finacial support from other countries and reopened some heritage sites for tourism to help rebuild |
| What are immediate responses | search and rescue and keeping survivors alive by providing medical care, food and shelter |
| What are long-term responses | re building and reconstruction, with the aim of returning people's lives back to normal and reducing future risk |
| Give reasons why people live in hazardous areas | -natural disasters do not occur very often -some people may not be aware of the risks of living close to a plate margin -better building design can withstand earthquakes so people feel less at risk |
| Where does Iceland lie? | On teh Mid-Atlantic Ridge, a constructive plate margin that stretches through teh middle of the Atlantic ocean |
| How does the tectonic activity in Iceland bring benefits? | -hot water from within the earth's crust provides heat and hot water -volcanic rocks are used in construction for roads and buildings -Thousands of tourists visited Iceland after the eruption of Eyjafjallajokull in 2010 |
| What are the 4 management strategies for reducing the risk from tectonic hazards? | -Monitoring -prediction -protection -planning |
| what is monitoring | using scientific equip to detect warning signs of events |
| What is prediction? | Using historical evidence |
| What is protection | Designing buildings thatw ill withstand the tectonic activity |
| What is planning? | identifying and avoiding places most at risk |
| Monitoring | -Scientific equip -seismicity (seismographs record earthquakes) -remote sensing (satellites detect chnages in heat and shape -gas is released as magma rises |
| Prediction | identify 'at risk' areas -yoklahoma tower in japan (flexible structure to absorb the movement of the ground shaking -san fran airpirt (rests on giant ball bearings) |
| protection | -mt Etna in Italy (earth embankments or explosives to divert lava away from property -earthquake drills help people keep alert and prepared -Chile (new buildings have reinforced concrete columns and a steel frame) |
| Planning | hazard maps produced (areas for evacuation) -restrcit development in certain places -protect vulnerable buildings suvh as hospitals |
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