Geography-Natural Hazards Flashcards
(105 cards)
1
Q
What are tectonic hazards?
A
A type of natural hazard
2
Q
What is a natural hazard?
A
A naturally occurring event that has the potential to affect people’s lives or property e.g. earthquakes, volcanic eruptions and tsunamis
3
Q
What are natural hazards called once they have affected peoples lives or property?
A
Natural disasters
4
Q
What are earthquakes and volcanoes examples of?
A
Tectonic hazards, caused by the movement of tectonic plates
5
Q
What is at the centre of the Earth?
A
The core, it has an inner bit and an outer bit. The inner core is a ball of solid iron and nickel. The outer core is liquid
6
Q
What is around the core?
A
The mantle, which is semi-molten rock that moves very slowly
7
Q
What is the outer layer of the Earth?
A
The crust, its very thin, about 20km
8
Q
What is the crust divided into?
A
Tectonic plates. They float on the mantle. Plates are made of two types of crust
9
Q
What are the two types of crust?
A
Continental crust which is thicker and less dense. Oceanic crust which is thinner and more dense
10
Q
Why are the plates moving?
A
Because the rock in the mantle underneath them is moving
11
Q
What are the places called where the plates meet?
A
Boundaries or plate margins
12
Q
What are the three types of plate margin?
A
Destructive margins, constructive margins and conservative margins
13
Q
What are destructive margins?
A
Where two 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. This often creates volcanoes and ocean trenches. Or where two continental plates meet, the plates smash together but no crust is destroyed
14
Q
What is a collision zone?
A
The area where continental plates collide
15
Q
What is a subduction zone?
A
The area where an oceanic plate is being pushed under a continental plate
16
Q
What are examples of destructive margins?
A
The pacific plate is being forced under the Eurasian plate along the east coast of Japan
17
Q
What are constructive margins?
A
Where two plates are moving away from each other. Magma (molten rock) rises from the mantle to fill the gap and cools, creating new crust
18
Q
What are examples of constructive margins?
A
The Eurasian plate and the North American Plate are moving apart at the mid-Atlantic ridge
19
Q
What are conservative margins?
A
Where two plates are moving sideways past each other, or are moving in the same direction but at different speeds. Crust isn’t created or destroyed. Either plates moving sideways past each other or plates moving in the same direction at different speeds
20
Q
What are examples of conservative margins?
A
The pacific plate is moving past the north american plate on the west coast of the USA e.g. at the San Andreas fault
21
Q
How can earthquakes occur on destructive margins?
A
Pressure builds up when one plate gets stuck as its moving down past the other into the mantle
22
Q
How can earthquakes occur on constructive margins?
A
Pressure builds along cracks within the plates as they move away from each other
23
Q
How can earthquakes occur on conservative margins?
A
Pressure builds up when plates that are grinding past each other get stuck
24
Q
What happens when the pressure that is built up gets too high?
A
The plates eventually break past each other, sending out shock waves (vibrations). These vibrations are the earthquakes. The shock waves spread out from the focus-the point in the Earth where the earthquakes starts
25
What is the epicentre?
The point on the Earths surface straight above the focus. Near the epicentre the shock waves are stronger and cause more damage?
26
How is the amount of energy released by an earthquake (magnitude) measured?
Using the Richter scale. The scale doesn't have an upper limit and its logarithmic-meaning an earthquake with a magnitude of 5 is ten times more powerful than one with a magnitude of 4
27
What plate margins are volcanoes found at?
Destructive and constructive margins
28
How do volcanoes form on destructive margins?
The oceanic plate goes under the continental plate because its more dense. The oceanic plate moves down into the mantle where its melted and destroyed. A pool of magma forms. The magma rises through cracks in the crust called vents. The magma erupts onto the surface where its called lava, forming a volcano
29
How do volcanoes form on constructive margins?
The magma rises up into the gap created by the plates moving apart, firing a volcano
30
Where else do some volcanoes form?
Over parts of the mantle that are really hot (hotspots) e.g. in Hawaii
31
What two kinds of impacts do earthquakes have?
Primary (immediate effects of ground shaking) and secondary (effect that happen later on)
32
What are some primary impacts of earthquakes?
Buildings/bridges collapse, people injured/killed by the collapses, transport links destroyed, electricity cables damaged-cutting off supplies, gas pipes broken causing leaks and cutting off supplies, telephone poles/cables destroyed and underground water/sewage pipes are broken causing leaks and cutting off supplies
33
What are some secondary impacts of earthquakes?
They can trigger landslides and tsunamis which cause more damage, leaking gas can be ignited and start a fire, people left homeless, psychological problems if they knew people that died or lost their home etc, shortage of clean water/lack of proper sanitation-easier for disease to spread, roads blocked/destroyed so emergency vehicles cant get through and businesses are damaged/destroyed causing unemployment
34
What part of the world do earthquakes have greater impacts?
LEDCs
35
Why do earthquakes have bigger impacts in LEDCs?
More poor quality housing which are less stable and destroyed easily, infrastructure often poorer, poor roads make it harder for emergency vehicles to reach injured people causing more deaths, don't have much money to protect against earthquakes or enough money and resources to react straight away so more people are affected by secondary impacts and healthcare is often worse in LEDCs, many hospitals don't have enough supplies to deal with the large number of casualties so people die from treatable injuries
36
Why don't people move away from earthquake prone areas e.g. California?
They've always lived there so they would have to leave friends and family. They're employed in that area so they'd have to find new jobs. They're confident of the support from their government after an earthquake e.g. to help rebuild houses. Some people think that sever earthquakes won't happen again in the area so its safe to live there
37
What are the different ways of reducing the impacts of earthquakes?
Predictions, building techniques, planning, education and aid
38
How can prediction reduce the impact of earthquakes?
Its impossible to predict when earthquakes will happen, if you could, to would give people time to evacuate, reducing injuries and deaths. There can be clues e.g. lots of small tremors, cracks in rocks and strange animal behaviours e.g. rats abandoning nests. Its possible to protect where they may happen using data from past earthquakes e.g. mapping err they've happened showing what places are more likely to be affected again, so these places can prepare for the impacts of an earthquake
39
How can building techniques reduce the impact of earthquakes?
Buildings can be designed to withstand earthquakes e.g. by using materials like reinforced concrete or building special foundations that absorb an earthquakes energy. Constructing earthquake-proof buildings reduces the number of buildings destroyed by an earthquake, so fewer people will be killed, injured, made homeless and unemployed
40
How can planning reduce the impact of earthquakes?
Future developments (shopping centres) can be planned to avoid most at risk areas reducing buildings destroyed, Firebreaks made to reduce spread of fires. Emergency services can train/prepare for disasters, practising rescuing people from collapsed buildings reducing amount of people killed. Governments can plan evacuation routes reaching injured and deaths
41
How can education reduce the impact of earthquakes?
Governments and other organisations can educate about what to do if theres an earthquake e.g. stand in a doorway, and how to evacuate, reducing deaths. People can be told how to make a survival kit containing things like food, water, a torch, radio and batteries, reducing the chance of people dying if their stuck in the area
42
How can aid reduce the impact of earthquakes?
LEDCS that have been affected can receive aid from governments or organisations, it can be things like food, water, money or people like doctors or rescuers. Aid helps reduce impacts e.g. money aid used to rebuild homes, reducing homelessness
43
Is predicting earthquakes a sustainable strategy?
No because its not effective
44
Why are the other strategies mentioned previously sustainable?
They're all effective and environmentally friendly, but some are more sustainable than others
45
What sort of strategies are more sustainable?
The ones that are more cost-effective. Some may be more expensive but more sustainable because in the long term, less money and resources are used to rebuild
46
What is the case study for an earthquake in an MEDC?
In L'Aquila, Italy on the 6th April 2009. 6.3 on Richter scale. Caused by movement along a crack in the plate at a destructive margin. Damage cost around $15 billion
47
What were the primary impacts?
Around 290 deaths, mostly from collapsed buildings. Hundreds were injured, thousands of bridges/buildings were damaged/destroyed. A bridge near the town of Fossa collapsed, and a mains water pipe was broken near the town of Pagancia
48
What were the secondary impacts?
Aftershocks stopped rescue efforts and caused more damage. Thousands of people were made homeless. Fires in some collapsed buildings caused more damage. The broken water pipe near the town of Pagancia caused a landslide
49
What were the reasons for the severity of the impacts?
Emergency services rescued survivors while cranes/diggers removed rubble, reducing people killed as injured people were rescued quicker. International teams helped. Camps set up for homeless people. Laws on construction standards were in place to withstand earthquakes so some didn't collapse however some modern buildings weren't built right increasing deaths and cost damage. Italy has a civil protection department training volunteers to help things like this reducing impacts
50
What is the case study for earthquakes in an LEDC?
In Kashmir, Pakistan. 8th October 2005. 7.6 on Richter scale caused by movement along a crack in the plate at a destructive margin. Damage cost about $5billion
51
What were the primary impacts?
About 80000 deaths mostly from collapsed buildings. Hundreds of thousands people injured. Entire villages and thousands of buildings destroyed. Water pipelines and electricity lines were broken, cutting off supply
52
What were the secondary impacts?
Landslides buried buildings and people, blocked roads and cut off water/electricity/phone access. Around 3 million people made homeless. Diarrhoea and other diseases spread due to little clean water. Freezing winter conditions shortly after earthquake caused more casualties and made rescues and rebuilding operations more difficult
53
What were the reasons for the severity of the impacts?
Buildings weren't built for earthquakes, increased deaths and damage cost. Few badly constructed roads, help couldn't arrive in some areas for weeks. People rescued by hand with no equipment or help from emergency services, increased death as injuries weren't treated quick enough. International aid teams eventually arrived so some were helped reducing deaths. Tents, blankets and medical supplies were distributed within a month but not to all areas, reducing homelessness and injuries were treated but only in some areas
54
Why do people live near volcanoes despite the danger?
The soil around the volcano is fertile as its full of minerals from volcanic ash and lava making it good for grown crops, attracting farmers. Volcanoes are tourist attractions, loads of tourists visit so loads lover around them to work in the tourist industry. Volcanoes are a source of geothermal energy, which can be used to generate electricity so people live around them to work at power stations
55
What are the primary impacts of volcanoes?
Buildings and roads are destroyed by lava flows and pyroclastic flows-buildings also collapse if enough ash falls on them. People and animals are injured or killed, mainly by pyroclastic flows but also by lava flows and falling rocks. Crops are damaged and water supplies are contaminated when ash falls on them. people, animas and plants are suffocated by carbon dioxide
56
What are the secondary impacts of volcanoes?
Mudflows (lahars) form when volcanic material mixes with water e.g. rain/snow. Cause loads of destruction/death/injuries. Fires started by lava flows and pyroclastic flows which spread. Psychological problems by death and loss of home, homelessness. Food shortage as crops are damaged, clean water shortage, roads blocked/destroyed so aid/emergency services cant get through. Businesses damaged/destroyed causing unemployment. Sulphur dioxide in atmosphere causes acid rain
57
How can prediction reduce impacts of volcanic eruptions?
Possible to roughly predict when they'll happen, can monitor signs before an eruption like tiny earthquakes, escaping gas and changes in the shape of a volcano e.g. bulges in the land where magma has built up underneath. Predicting eruptions give people time to evacuate, reducing injuries and deaths
58
How can planning reduce impacts of volcanic eruptions?
Future developments can be planned to avoid at risk areas, reducing destruction. Firebreaks to reduce spread of fires. Emergency services can train and prepare. Governments can prepare evacuation routes
59
How can building techniques reduce impacts of volcanic eruptions?
Buildings cant be designed to withstand lava flows or pyroclastic flows but they can be strengthened so they're less likely to collapse under weight of falling ash. Lava from some volcanoes can be diverted away from buildings with barriers. Both of these reduce number of buildings destroyed, so fewer deaths/injuries/homelessness/unemployment
60
How can education reduce impacts of volcanic eruptions?
Governments and other organisations educate on evacuation which reduces deaths. People can be taught how to make a survival kit
61
How can aid reduce impacts of volcanic eruptions?
Aid from governments or organisations and helps to reduce impacts e.g. food aid stops starvation
62
What are climatic hazards caused by?
Weather
63
What are tropical storms?
Intense low pressure weather systems and can be called hurricanes, typhoons and tropical cyclones. They have strong winds and torrential rain
64
What conditions are needed for a tropical storm to form?
They develop over sea water thats 27ºC or higher. Happen when sea temperatures highest so different times for different places. Warm, moist air rises and condensation occurs releasing huge amounts of energy making them really powerful
65
When do tropical storms occur?
August to October in the atlantic. May to December in the north east pacific
66
How do tropical storms travel?
They move west because of the easterly winds near the equator.
67
What happens when tropical storms make landfall?
They lose strength because the energy supply from the warm water is cut off
68
Where do most tropical storms occur?
Between 5º and 30º north and south of the equator e.g. in the Atlantic and then Indian ocean, any further from the equator and the water isn't warm enough
69
What are the characteristics of tropical storms?
Spin anticlockwise and move north west in the northern hemisphere. Circular shape, can be hundreds of kilometres wide. Usually last from 7-14 days. Centre is called the eye, up to 50km across and caused by descending air, usually very low pressure, light winds, no clouds, no rain. Eye is surrounded by eyeball, spiralling rising air, very strong winds around 160km per hour, storm clouds and torrential rain. Towards the edges of the storm the wind speed falls, the cloud size decreases and the rain is less intense
70
What are storm surges?
Large rises in sea level caused by the low pressure ad high winds of a storm
71
What are the primary impacts of tropical storms?
Buildings/bridges destroyed. Rivers/coastal areas flooded. People drown, or they're injured or killed by debris thats blown around. Transport links damaged. Electricity cables damaged and cut off. Telephone cables destroyed. Sewage overflows due to flooding, sewage contaminates water supplies. Crops damaged. Livestock killed. Heavy rain makes hills unstable causing landslides. Beaches are eroded and coastal habitats (corral reefs) destroyed
72
What are the secondary impacts of tropical storms?
People left homeless. Clean water shortage. Lack of proper sanitation so easier for disease to spread. Emergency vehicles cant get through due to damaged transport links. Businesses are damaged/destroyed causing unemployment. Food shortage because crops are damaged and livestock is dead. Psychological problems from death
73
How can tropical storm impact be reduced?
Same as for earthquakes and volcanoes but also storm tracking, radar, satellites, computer models etc, flood defences
74
What is the case study for a tropical storm in an MEDC?
Hurricane Katrina, south east USA, 29th August 2005, damage cost around $300 billion
75
What were the primary impacts?
More than 1800 deaths. 300000 houses destroyed. 3million left without electricity. One of the main routes out of New Orleans was closed as parts of the 1-10 bridge collapsed. Coastal habitats such as sea turtle breeding beaches were damaged
76
What were the secondary impacts?
Tens of thousands made homeless. 230000 jobs lost from businesses that were damaged or destroyed. Water supplies were polluted with sewage chemicals and dead bodies
77
What were the reasons for the severity of the impact?
USA has sophisticated monitoring system, 70-80% of new orleans residents were evacuated. Control centres and stockpiled supplies reduced impact. Emergency services rescued over 50000 people reducing deaths. However flood defences failed increasing deaths and damage costs
78
What is the case study for tropical storms in an LEDC?
Cyclone Nargis in Irrawaddy delta, Burma. 2nd May 2009. Damage cost around $4 billion
79
What were the primary impacts of the tropical storm?
More than 140000 deaths. 450000 houses destroyed. 1700 schools destroyed. 200000 farm animals killed, crops lost. Over 40% of food stores destroyed. Coastal habitats such as mangrove forests damaged
80
What were the secondary impacts of the tropical storm?
2-3 million people made homeless. Millions of people lost their livelihoods. Over 70% of households didn't have access to clean water
81
What were the reasons for the severity of the impact?
Indian and Thai weather agencies warned the Burmese government about the storm but they still reported there was little or no risk to their people increasing deaths as people didn't evacuate. There were no emergency/evacuation plans. The government initially refused to accept foreign aid, only agreeing to it 3 weeks later increasing deaths from injuries. Aid was eventually accepted including tents, blankets and medicines reducing some deaths
82
What is a drought?
A drought is a long period when rainfall is below average
83
What happens to water supplies during a drought?
Lakes and rivers are depleted because people keep using them but they aren't replenished by rainfall. Also droughts are often accompanied by high temperatures which increases the rate of evaporation
84
How long do droughts last for?
Its different in different places eg the longest one n britain lasted 16 months, but in african countries they can last for more than a decade
85
What are the climatic causes of drought?
When changes in atmospheric conditions mean it doesnt rain much in an area for years eg in Ethiopia. Changes in the atmospheric circulation can also make the annual rains fail (no monsoons in places like India). Also cause when high pressure weather systems (anticyclones) block depressions (weather systems that cause rains) like in the UK
86
What areas are most at risk of drought?
North-eastern Africa, the sahel, southern africa, middle eastern australia and parts of eastern south american and indonesia
87
Why do people sill live in drought prone areas?
They've always lived there, they have a job in the area and they dont think a drought will happen again soon etc
88
What are the causes of desertification?
Deforestation, rainfall failure, climate change, overgrazing, soil erosion, overpopulation and over cultivation
89
How can deforestation cause desertification?
Nutrients in soil comes from the leaves that fall off the trees, if there are no trees there is no nutrients being added to the soil so if the wind blows there is no trees to protect the soil, and the wind blows away the nutritious top layer of soil, leaving you with low quality soil
90
How can rainfall failure lead to desertification?
No rain means soil dries out so its easier to blow away, leaving only low quality soil
91
How can climate change lead to desertification?
Hotter and drier weather means soil is drier and easy to blow away, leaving the low quality soil
92
How can over grazing lead to desertification?
More cattle means more grass is being eating and grass helps to bind the soil together, without grass it can easily blow away and leave only the low quality soil
93
How can soil erosion lead to desertification?
Erosion takes away the top layer of nutritious soil, leaving the low quality soil
94
How can overpopulation lead to desertification?
Bigger population means more water being dunk. Water comes from the soil so it dries out and can then blow away, leaving the low quality soil
95
How can over cultivation lead to desertification?
Bigger population means more food being eaten, land will then be farmed intensively and takes out the nutrients each time. LEDCs cant afford artificial nutrients and so eventually they are left with low quality soil
96
What are the primary impacts of drought?
Vegetation dies, people and animals die from dehydration, aquatic animals die because rivers and lakes dry up, soil dries out and is easily eroded by wind and rain
97
What are the secondary impacts of drought?
Animals die from starvation as no vegetation. Food shortage as crop fail and livestock die so humans die from starvation. Desertification. Conflict over water supplies/ People move out of area to find water. Farms close (unemployment), psychological issues due to stress from business losses. Wild fires as dried out vegetation is easily ignited by eg lightning. Winds pick up dry soil causing dust storms
98
What human activities increase the impacts of drought?
Overgrazing (same reason as for desertification) and excessive irrigation (same effect as depleted water supplies)
99
Why are impacts of drought more severe in LEDCs?
More people depend on farming so if crops and livestock die, lots of people may starve. They also have less money to prepare for droughts or respond to them eg they cant afford to build reservoirs so the impacts of a drought are more severe
100
How can you reduce the impacts of drought?
Prediction, farming techniques, water conservation, increase water supplies and aid
101
How can prediction reduce the impacts of drought?
They can be predicted a short time before they happen by monitoring rainfall, soil moisture and river levels. When a drought is predicted, things can be done to reduce the impacts eg banning hosepipes, rationing water or moving people out of areas that will be worst affected
102
How can farming techniques reduce the impacts of drought?
Drought-resistant crops can be grown eg millet, sorghum and olives. More efficient methods of irrigation can be used. For example, drip irrigation delivers small volumes of water directly to crop roots (reducing amount lost by evaporation) these techniques reduce the demand on water supplies and make food production more reliable
103
How can water conservation reduce the impacts of drought?
People can conserve water by reducing the amount they use in their homes eg by installing low volume flush toilets, and by showing instead of baths. Can also install water butts at home to collect rainwater and use it to wash their car or water their garden. These reduce the demand on water supplies, so more water is available during a drought
104
How can increasing water supplies reduce the impacts of drought?
Reservoirs and wells can be built to increase water supplies. These make more water available during a drought reducing deaths from dehydration, reducing conflicts over supplies and making food production more reliable
105
How can aid reduce the impacts of drought?
Can help reduce impacts of drought in more than one way, emergency aid like food and water tankers can stop people dying from dehydration or starvation. Aid can be used to fund development projects eg building wells or water pipes to make more water available during droughts
