Unit 1 A The Challenge Of Natural Hazards Flashcards
Describe plate tectonic theory
Made up of 2 types of crust; continental and oceanic. Continental is thicker and less dense whereas oceanic is thinner and more dense. The plates are moving because of convection currents in the mantle underneath. Place where plates meet are called plate margins or plate boundaries
What are destructive margins
Where 2 plates are moving towards each other.where an oceanic plate meets a continental plate,the denser oceanic plate is forced down into the mantle and destroyed a pool of magma forms the magma rises through cracks in the crust called vents, the magma erupts into the surface forming a volcano and ocean trenches are also formed .
What are constructive margins
Where 2 plates are moving away from each other.magna rises from the mantle to fill the gaps forming volcanoes then cools,creating new crust.earthquakes also occur as tension builds along cracks within the plates . An example is the mid-Atlantic ridge
What are conservative margins
Where 2 plates are moving sideways past each other or are moving in the same direction but at different speeds. Earthquakes occur and Crust isn’t created or destroyed. An example is the San Andreas fault in California
4 Primary effects of an earthquake
- buildings and bridges collapse, and homes are destroyed
- people are injured or killed by collapsed building and falling debris
- roads,railways,ports and airports are damaged
- electricity cables,gas and water pipes and communications networke are damaged cutting off supplies
4 secondary effects of earthquakes
- can trigger landslides and tsunamis
- aid and emergency vehicles can’t get through and trade is difficult
- people are left homeless and could die
- there’s a shortage of clean water and a lack of proper sanitation, easier for disease to spread
4 immediate responses to an earthquake
- rescue people trapped by collapsed buildings and treat injured people
- set up temporary shelters for people whose homes have been damaged/destroyed
- provide temporary supplies of food,water,electricity,gas and communication systems if reg supplies have been damaged
- recover dead bodies to prevent disease spread and put out fires caused by leaked gas
4 long term responses to earthquakes
- Re-house people who lost their homes
- repair or rebuild damaged buildings,roads,railways and bridges
- reconnect broken electricity, water, gas and communication connections
- set up initiatives to help economic recovery
4 primary effects of a volcanic eruptions 🌋
- buildings and roads destroyed by lava and pyroclastic flows
- people and animals are injured by pyroclastic and lava flows and falling rocks
- crops are damaged and water supplies are contaminated when ash falls on them
- people,animals and plants are suffocated by volcanic gases
4 secondary effects of volcanic eruptions 🌋
- mudflows and landslides may form if volcano material mixes with water and cause more destruction,death and injury
- flooding can be caused by hot rock ash and gas melting ice and snow on the volcano, rock and ash can clog rivers making flooding even worse
- tourism can be disrupted straight after an eruption but often increases afterwards
- ash makes fields more fertile once it’s broken down
4 immediate responses to volcanic eruptions
- evacuate people before or asap after
- provide food,drink and shelter for evacuees
- rescue people cut off by damage to roads or bridges
- foreign governments or charities may send aid workers,supplies,equipment or financial donations
4 Long term responses to volcanic eruptions
- Repair and rebuild if possible or resettle affected people elsewhere
- repair and reconnect infrastructure
- improve, repair and update monitoring and evacuation from plans
- boost economy if possible( by attracting tourists)
2 Primary effects of an earthquake in higher income country L’aquila,Italy 6th April 2008 , size 6.3
- 300 deaths and 1500 people injured
- over 60,000 people were made homeless
2 Secondary effects of an earthquake in higher income country L’aquila,Italy 6th April 2008 , size 6.3
- fires in some collapsed buildings caused more damage
- the broken water pipe near the town of pagan is caused a landslide
2 immediate responses of an earthquake in higher income country L’aquila,Italy 6th April 2008 , size 6.3
- camps were set up for people made homeless providing water,food and medical care
- money was provided by government to pay rent and gas and electricity bills were suspended
2 Long term responses of an earthquake in higher income country L’aquila,Italy 6th April 2008 , size 6.3
- new settlements were built to accommodate over 20,000 residents who were affected
- most of city centre is being rebuilt but there has been criticisms over delays
2 primary effects of an earthquake in a lower income country Kashmir, Pakistan 8th October 2005 size 7.6
- 80,000 dead and tens of thousands people injured
- 3 million people made homeless
2 secondary effects of an earthquake in a lower income country Kashmir, Pakistan 8th October 2005 size 7.6
- landslides buried buildings and people also blocked access roads and cut off water supplies,electricity supplies and telephone lines
- diarrhoea and other diseases spread due to little clean water
2 immediate responses of an earthquake in a lower income country Kashmir, Pakistan 8th October 2005 size 7.6
- tents,blankets and medical supplies were distributed but took up to a month to reach some areas
- help didn’t reach many areas for days or weeks and many people had to be rescued without any equipment or help from emergency services
2 long term responses of an earthquake in a lower income country Kashmir, Pakistan 8th October 2005 size 7.6
- 40,000 people relocated to a new settlement
- aid was given to rebuild schools and government money was given to rebuild homes after 3 years people still living in tents and no schools still not rebuilt after 10 years
Reasons why people live in areas at risk from tectonic hazards
- they’ve always lived there
- they’re employed in the area
- people are confident in the support from their government
- think a severe hazard may not happen again
Management strategies: monitoring
- Networks of seismometers and lasers monitor earth movements and can be used in early warning systems.
- scientists can monitor the signs that come before a volcanic eruption e.g. Tiny earthquakes,escaping gas and changes in shape of voocano
Management strategies: prediction
- earthquakes cannot be reliably predicted,but by monitoring the movement of tectonic plates scientists can forecast which areas should be prepared for one
- volcanic eruptions can be predicted if the volcano is well monitored
- prediction gives people time to evacuate reducing injuries and death
Management strategies: protection
- buildings can be designed to withstand earthquakes
- existing buildings and bridges can be strengthened
- automatic shut off switches can fitted that turn off has and electricity supplies to prevent fires
Management strategies: planning
- future developments can be planned to avoid the areas most at risk from tectonic hazards
- emergency services can train and prepare for disasters
- people educated so know what to do in hazard
- evacuation routes planned so people can get out of dangerous areas quickly and safely
- emergency supplies stockpiled
What are differences in air pressure caused by
Differences in temperature between the equator and the poles, winds move from the areas of high pressure to the areas of low pressure
How does global atmospheric circulation lead to high and low pressure belts
- at equator sun warms earth,transfers heat to air above causes to rise.creates low pressure belt with rising air,clouds and rain
- as air rises it cools and moves out to 30° north and south of equator
- 30°north and south of equator cool air sinks creating high pressure belt with cloudless skies and low rainfall
- cool air reaches ground surface and moves as surface winds either back to equator or towards poles
- 60° north and south of equator warmer surface winds meet colder air from poles.warmer air less dense than cold do rises creating low pressure
- some air moves back towards equator,rest moves towards poles
- at poles cool air sinks creating high pressure this if drawn back towards equator as surface wind
When do tropical storms develop
- when sea temp is 27°c or higher
- when wind shear between higher and lower parts of the atmosphere is low
- warm,moist air rises condensation occurs.this Releases huge amounts of energy makes storm powerful, rising air creates area of low pressure which increases surface winds
