Great A-level AQA Hazards Flashcards

What is a natural hazard?

Naturally occurring event with the potential to harm people and properties. 

What occurs in relief stage of Park model?

This is where the immediate responses to a disaster occur and the responses closest to the actual event.

What is fatalism?

A belief that natural hazards are unavoidable and that individuals should accept the consequences instead of taking preventative measures.

What is prediction?

The process of forecasting future hazards based on data and analysis, often aiming to mitigate their impact such as satelite imagery to track storms.

What is adjustment/adaptation?

The process by which individuals or communities modify their behaviour and systems in order to live with hazards and reduce the impact of them such as regular evacuation drills.

What is management?

Identifying and prioritising risk such as hazard action plans.

Risk sharing?

Measures to spread the burden of a hazard such as emergency relief funds using tax revenue from other locations.

How does the time interval between disasters impacts on an areas response to these disasters?

Significantly as if hazards occur within a short duration of each other the hazard management cycle may not be complete meaning the recovery will likely not be completed and impacts of the original hazard will be more severe.

Describe the main features of the oceanic crust?

-6-10 km thick, mainly basalt, dense (3.0 gm per cm cubed).

-Less than 200 million years old. Forms ocean floor thin outer layers and constantly recycled at subduction zones.

-Around 1000 degrees celsius base temperature and around 0 degrees celsius on surface. 

Describe the main features of the continental crust? 

-Forms the landmasses, thicker than oceanic crust and 30-70 km thick.

-Around 1000 degrees celsius base temperature and around 0 degrees celsius on surface.

-Mainly granite rich in silica, 2.7 (gm per cm cube) less dense than oceanic. Old with some parts around 4 billion years old. 

Describe the main features of the asthenosphere? 

• Upper part of the mantle below the lithosphere. 

• 100 km-300 km deep

• Around 1300 degrees celsius

• Semi-molten flows allowing plates to move

• Rich in iron and magnesium silicates 

Describe main features of the mantle?

• Extends base of crust to around 2900 km deep.

• Temp of around 1000 degrees celsius at the upper regions and around 3700 degrees celsius around lower regions

• Solid silicate rocks rich in magnesium and iron

• Largest layer be volume and convection currents which is where hotter, less dense fluid rises causes plate tectonics.

Describe main features of the core?

Outer core is around 2900 km-5100 km deep. Around 4000-5000 degrees celsius. Liquid iron and nickel, the iron generates earth’s magnetic field.

Inner core is around 5100-6371 km deep. Around 6000 degrees celsius. Solid iron and nickel due to pressure and densest layer.

What is sea floor spreading?

The process by which new oceanic crust is formed by rising magma, which solidifies and pushes away older crust away on either side. 

How does mantle convection hypothesis explain plate movement at plate boundaries?

It suggests that the heat from the Earth’s core causes convection currents in the asthenosphere. These currents drag the overlying lithospheric plates, causing them to move.

Explain formation of mid-ocean ridge from a rift valley?

• At constructive plate boundaries or hotspots lithosphere is pulled apart. The continental crust is stretched creating faults.

• As faults develop the crust sinks and a rift valley is formed.

• Then rising magma may met crust and as the crust sinks below sea level a linear sea ifs formed and then a mid ocean ridge can form.

What is the mantle composed of?

• Three separate layers the lithosphere, asthenosphere and lower mantle.

• The lithosphere is solid and commonly referred to as the crust.

• The asthenosphere is semi-molten allowing plates to move and lower mantle is denser and higher temperatures.

Why do earthquakes at constructive plate boundaries have shallow foci and cause little damage?

• Moving apart of plates causes stress in crust. The earthquake occurs in upper few kilometers of crust where it is brittle so foci is shallow

• Plates pull apart slowly and smoothly so less built up stress and energy released

What is the foci of an earthquake? 

The point inside the crust which the earthquake originates from 

Magmas and lavas at constructive plate boundaries have low silica content. How does silica content affect nature of volcanic eruptions?

Low silica content affects viscosity (the ability to trap gasses). High basaltic which has low silica, so magma flows easily and eruptions are usually gentle and less explosive.

How does subduction causing earthquakes at destructive plate boundaries occur and what are both ways?

• In oceanic-continental boundaries the denser oceanic plate subducts and friction and stress build up from this forms earthquakes. Also, melted crust material is welled up and out by volcanoes.

• At oceanic-oceanic plate boundaries, one oceanic plate subducts which is the older and denser one with the friction and stress causing earthquakes.

What are eruptions like at destructive oceanic-oceanic plate boundaries?

• Lower silica content than oceanic-continental and less viscous with less gas trapped. 

• Still explosive but with less gas trapped this is lower. 

What are eruptions like at oceanic-continental destructive plate boundaries?

• Have intermediate silica content higher than oceanic-oceanic, meaning magma is thicker and sticky

• More trapped gases increase pressure and thus explosivity

Why do collision (destructive) plate boundaries produce many earthquakes?

When plates push against each other they cause continental stress. Due to both being thick and similarly dense, stress builds up and releases earthquakes. Can be very powerful as released in one go and crust volume can be large.   

What are collision plate boundaries?

A type of destructive (convergent) plate boundary where two plates move towards each other where neither one is dense enough to subduct. Which causes the plates to crumple and fold upwards forming fold mountains.

Why are earthquakes at conservative plate boundaries potentially so destructive.

At conservative plate boundaries, plates move past each other. Friction prevents smooth sliding so stress can accumulate over years or decades. One sudden movement can release all this built up energy and no prior activity makes prediction hard.

Named examples, location, description and tectonic context of mid ocean ridges?

Mid Atlantic ocean ridge, between European and American land masses, long underwater mountain range from upwelling of magma and occurs at constructive plate boundaries.

Named examples, location, description and tectonic context of rift valleys?

East African rift valley, Ethiopia, Long narrow sunken valley caused by faults in crust by upwelling of magma and occurs at constructive plate boundaries. 

Named examples, location, description and tectonic context of young fold mountains?

Himalayas, Nepal, High steep mountains formed by plates colliding and crumpling upwards and occur at collision plate boundaries.

Named examples, location, description and tectonic context of deep sea trenches?

Mariana trench, West pacific ocean, Very deep narrow trench where the subduction of the oceanic plate sink into mantle and occurs at destructive plate boundaries.

Named examples, location, description and tectonic context of island arcs?

Japanese islands, Western Pacific, Curved chain of volcanoes parallel to deep sea ocean trench caused by upwelling of magma and rock from subduction of oceanic plate and occurs at destructive oceanic-oceanic plate.

How do moving plates and magma plumes form island chains?

• Mantle plume is upwelling of hot magma from a hotspot.

• Stationary as plates move and volcanoes form islands with repeated eruptions

• As plates move original volcano is moved and becomes dormant

• New volcanoes are produced and this repeats forming an island chain

Name and locate an example, explain the causes and describe the effects of nuees ardentes (pyroclastic flows)?

• Mount Pelee, Martinique 1902 eruption 

• Collapse of a lava dome or eruption column released superheated gases, ash and rock fragments down slope at around 100 km/h

• 30,000 killed and city of saint pierre was destroyed.

Name and locate an example, explain the causes and describe the effects of lava flows

• Nyriagongo 2002 in the DRC.

• Low viscosity balsatic lava erupted from fissures moving rapidly up to 60km/h 

• 120,000 displaced, 15% of Goma covered in lava

Name and locate an example, explain the causes and describe the effects of mudflows? 

• Nevaso del Ruiz 1985 in Colombia. 

• Eruption melted glaciers and snow, which mixed with volcanic ash, creating fast-flowing mudflows down river valleys.

• Town of Armero was buried. 23,000 killed and mudflows (lahars) up to 100km/h.

Name and locate an example, explain the causes and describe the effects of pyroclastic and ash fallout (tephra)?

• Mount Pinatubo 1991 in the Phillipenes.

• Explosive eruption ejected vast amounts of ash into stratosphere (VEI 6) with heavy ash fall

• Global temperatures fell by 0.4 degrees celsuis for two years because erupted sulphur dioxide was converted into suplhate aerosols that reflected sunlight. 

Name and locate an example, explain the causes and describe the effects of gases/acid rain?

• Laki Fissure Eruption 1783-1784 in Iceland

• Lage balsatic fissure eruption released massive amounts of sulphur dioxide, fluorine and other gases. SO2 combined with water to form sulphuric acid rain.

• Crops failed, livestock died, famine killed 20% of Iceland and acid rain over Europe caused respiratory issues and crop failures as well.

Outline two ways to predict volcanic hazards?

• 1. Seismic activicty (Earthquakes&Tremors). Rising magma fractures rock as it moves upwards. Monitoring seismicity helps scientists detect magma as it apporaches the surface.

• 2. Ground deformation and Gas emissions. GPS and tiltmeters detect swelling of volcaneo as magma accumulates.While increase in suplhur dioxide or carbon dioxide emissions signal rising magma .

What steps can be taken by individuals and organisations to reduce the impact of volcanic hazrads?

• Prediciton and monitoring through seisometers, tilt meters and gas detectors help detect early signs of eruption which then allows evacuation for those at risk to take place.

• Planning and prepartion through hazard maps to signal high risk zones and prevent settlements in these areas. Also education training can improve population preparedness to respond to hazards.

For one recent hazrdous volcanic event name and locate the event, briefly describe the hazardous nature of the event, outline the social, economic and environmental impacts and describe the human responses to the event?

• Ontake 2014 in Japan

• Pheratic eruption where magma came into contact with ice and snow causing a huge explosion leading to lots of material being released.

• Rescue and recovery costs were around 46 million US dollars. Total economic cost around 110 million US dollars. Around 63 people died and over 40 were seriously injured. Visitor numbers dropped 30-40% in following months

• 20 helicopters were deployed and over 1000 personal, including Japanese self defense forces, police, fire departments participated in rescue efforts. Long term responses included increased monitoring and real time data sharing with Japanese Meterolgical Agency. Hikers had to wear safety gear and allow tracking at certain locations. 

Name and locate an example, explain the cause and describe the effects of earthquakes/shock waves? 

• Tohoku 2011 in Japan

• Subduction of Pacific plate under North American plate along destructive plate boundary. At the Japanese sea trench a megathurst fault were 32,000 megatonnes of energy were released.

• Around 121,000 buildings were destroyed and plate dispalced around 40m. 

Name and locate an example, explain the causes and describe the effects of liquefaction?

• Christ Church 2011 in New Zealand

• Strong seismic force during an earthquake caused water saturated sediments beneath the city to lose strength and behave as a liquid.

• 15,000 homes were demolished with large scale sinking of infrastructure. 

Name and locate an example, explain the causes and describe the effects of landslides?

• Kashmir Earthquake 2005 in Pakistan

• 7.6 magnitude earthquake along a destructive plate boundary between Indian and Eurasian plates shook mountain slopes triggering landslides to occur.

• Thousands of landslides buried villages and blocked roads isolating communities from accessing aid. Estimated to of caused around 80,000 deaths.

Name and locate an example, explain the causes and describe the effects of tsunamis? 

• Tohoku 2011 in Japan 

• 9.0 magnitude earthquake on moment magnitude scale earthquake 70m east of oshika penisula caused a huge tsunami around 40m high. 

• Of the 15,800 who died 90% of deaths were estimated to be due to drowning. 

How can seismic gap theory help predict eartqhaukes?

It is the idea that sections of an active fault that haven’t experienced an earthquake for a long time (a gap) are likely to be the next place stress is released. Plates that haven’t released stress and remain locked likely to have major event.

What steps can be taken by individuals and organisations to reduce impact of seismic hazards?

Preparation, where building codes can be improved with a focus on dealing with seismic activity and regular evacuation drills so population preparedness is higher for disasters. Also response such as search and rescue can reduce deaths for example after event has occurred

For one recent hazardous seismic event, name and locate, described hazardous nature, outline impacts and describe human responses?

• Haiti 2010.

• 7.0 moment magnitude scale earthquake along a destructive plate boundary between North American and Caribbean Plate along Enqurillo Plantain Garden Fault.

• Around 230,000 people killed, 300,000 injured, economic costs of $8 billion which was 120% of Haitis GDP, more than 250,000 buildings destroyed

Very inadequate and incapable. Civil Protection Department responsible for disaster management only had 200 staff. 800,000 received water aid and 500,000 received food aid from foreign organisations

What is the structure of a typical revolving storm?

• Eye is centre. 20-50km wide. Calm weather and light winds as air sinks here

• Eye-wall has strongest wind and rain. Ring of towering Columbus clouds and air rises rapidly here.

• Spiral rain bands are bands of heavy thunderstorms and rainfall spiralling outwards from eye-wall which can be 100kms away. Spin direction depends on location and how this interacts with spin of the Earth.

Describe the processes involved in formation of a tropical storm?

• Sea surface temperatures must be at least 26-27 degrees Celsius and 60-70m deep. (This provides heat energy to storm)

• Warm ocean heats air above it causing it to rise and evaporate large amount is water vapour (low pressure at surface)

• Rising air condenses forming cumulonimbus clouds

• As more air rises more rushes in to replace it which causes a spiral inwards and low pressure system below forms storm

• When moving over land water is lost causing a loss in energy as storms pressure rises with less heat and moisture

Name and locate an example, explain the cause and describe the effects of high wind speeds?

• Hurricane Matthew 2016 in Haiti

• Low pressure in centre of storm caused air to rapidly move in down a pressure gradient at high speeds

• Sustained wind speeds of 135mph occurred which contributed to 546 deaths, 2.8 billion in economics costs which was 32% of Haitis GDP.

Name and locate an example, explain the cause and describe the effects of storm surge and coastal flooding?

• Hurricane Matthew 2016 in Haiti

• Strong winds push sea water towards coast and low pressure in eye causes sea levels to rise

• 9-15 feet storm surge in coastal regions

Contributed to 546 deaths and over 200,000 buildings being destroyed

Name and locate an example, explain the cause and describe the effects of Intense rainfall and river flooding?

• Typhoon Jebi 2018 in Japan

• Tropical storms carry huge amounts of warm and most air. When air condenses after rising rainfall is released

• Rainfall can cause river flooding which occurred as around 500mm of rainfall fell. $13.5 billion in economic damage and 27,500 properties damaged

Name and locate an example, explain the cause and describe the effects of landslides?

• Typhoon Haiyan 2013 in Philippines

• Prolonged or intense rainfall can saturate soil reducing its stability as ground gives way it can slide downhill causing landslides

• This occurred with Typhoon Haiyan in hilly areas and contributed to the 6,352 deaths that occurred

What steps can be taken by individuals or organisations to reduce impact of storm hazards?

Preparation, by evacuating areas at high risk, setting up sea walls to defend against storm surge. Responses as search and rescue can reduce deaths and ensuring people have access to clean water in the short term can prevent disease outbreaks such as cholera.

Why do early warning systems and evacuation reduce proportion of deaths and injuries?

Because early warning systems give people to evacuate which reduces deaths and injured as less people are in areas where the storm is most severe or low lying more prone to flooding.

How do human responses and impacts of tropical storms depend on level of economic development?

• They vary to a large extent

• This can be seen in preparation as Typhoon Jebi a category 3 storm damaged 27,000 buildings ranging from minor to severe due to strict building codes. Whilst Hurricane Matthew a category 4 storm destroyed 200,000 buildings

• Also in the response as after Typhoon Jebi emergency water distribution centres were set up but in Haiti only 60% of people have access to clean water anyway meaning more people suffer from further water insecurity.

• This is due to 3rd largest GDP in the world compared to 146th

For one recent tropical storm, name and locate an example, explain the cause and describe the effects?

• Typhoon Jebi 2018

• Category 3 typhoon in the Pacific. Sustained wind speeds of around 100mph. 500mm rainfall and 100mm rainfall in just one hour reported in areas such as Kyoto

• Around 17 people died and 600 were injured. Over 27,000 buildings suffered damage ranging from severe to minor.

• Over 1,100 shelters were set up across affected regions, water distribution centres set up, 1.6 million people evacuated and $4.5 billion allocated for immediate disaster relief

How do vegetation type, fire behaviour, recent weather conditions, climate and fuel characteristics impact wildfires?

• Dense vegetation that is dry acts as better fuel for the fire causing it to more rapidly expand. Also some vegetation fire resistant such as redwoods

• Fuel characteristics impact wildfires though size, moisture content and flammability all impacting the fire

• Climate impacts wildfires as high temperatures cause fire to grow and dry out vegetation

• Weather conditions influences fire as windy contains cause embers of fire to spread much faster and lightning can start fires.

• Fire behaviour is also important as steep slopes cause fires to travel faster and pyrocumulus clouds can form increasing fire

How can wildfires be started?

Can be started naturally by events such as lightning causing vegetation to set on fire. Also humans often cause wildfires by cigarettes thrown out of cars, campfires or intentional burnings.

What factors need to be taken into account when producing a wildfire risk assessment strategy?

Must account for physical factors such as weather conditions, topography and vegetation which in different areas greatly influence risk of fire. As well as human factors such as population density indicating the potential the fire actually has to harm humans and its risk.

How can fire management strategies actually contribute to severity of wildlife hazards?

Outdated practices such as fire suppression where all fires are immediately put out prevent low intensity natural fires. Meaning underbrush and dead matter remain as fuel leading to huge further fuelled wildfires.

For a recent wildlife you have studied, name and locate an example, explain the cause and describe the effects of

• Fort McMurray 2016 in Canada

• 590,000 hectares of forest were burnt by a wildfire which released 85 million tonnes of carbon dioxide into atmosphere. Cause unknown but 60% in Alberta human induced

• 37% of youth had PTSD and 15% of all residents post fire, calls to a local suicide hotline increased from 600 in 2015 and 400 in 2016 to 900 in Jan-Nov 2017

• Economic cost of around 10 billion Canadian dollars, slow down of production of a million barrels of oil a day cost 985 million. 2,400 buildings destroyed.

• Led to questions over quality of fire prevention and reviews into the strategies used to prevent wildfires with more controlled burns being introduced