| World at Risk |
What are Hazards?
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| World at Risk |
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| vulnerability.docx |
Watch the following TED talk, discuss and make a list of reasons why people chose to live in hazard areas. Create a table outlining all the possible reasons why people live in hazard zones.
Causes of earthquakes and volcanoes
Earthquakes
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Create a detailed set of notes on Earthquakes (use the Worksheet):
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Prediction?
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Earthquakes are extremely hard to predict. Scientists can normally predict where earthquakes are likely to happen, but they can not predict when they will happen and how strong they will be. Scientists can attempt to predict by looking at:
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Frequency
It is extremely difficult to asses whether any hazard is increasing in frequency because of two reasons:
The general consensus is that earthquakes are not increasing in frequency.
- We are better at detecting and reporting them due to improvements in technology
- We do not have an extensive record to draw from. Geological patterns can span hundreds of thousands of years but we only have accurate historical records spanning at most 100 years.
The general consensus is that earthquakes are not increasing in frequency.
Magnitude
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Uses a Seismograph and the magnitude of an earth is classified through the zig-zag trace that shows the varying amplitude of ground oscillations (as a result of seismic waves) beneath the instrument. Sensitive seismographs, which greatly magnify these ground motions, can detect strong earthquakes from sources anywhere in the world. The time, locations, and magnitude of an earthquake can be determined from the data recorded by seismograph stations.
The magnitude of an earthquake is determined from the logarithm of the amplitude of waves recorded by seismographs. On the Richter Scale, magnitude is expressed in whole numbers and decimal fractions. For example, a magnitude 5.3 describes a moderate earthquake, whilst 7.3 denotes a major earthquake Because of the logarithmic basis of the scale, each whole number increase in magnitude represents a tenfold increase in measured amplitude. As an estimate of energy, each whole number step in the magnitude scale corresponds to the release of about 31 times more energy. |
Moment magnitude scale
Developed in the 1970s. An earthquake produces many types of waves, which radiate from its epicenter and move with a wide variety of frequencies. Compared to the Richter scale, the moment magnitude scale can account for more types of these waves, and at more frequencies. It is thus better able to estimate the total energy of earthquakes, and can also relate these observations to the physical features of a fault.
Mercalli Scale
A behavioral type classification of the resulting damage caused by earthquakes. It helps draw picture of the impacts along a transect from the epicenter. Rather than follow abstract logarithmic scale it describes the physical and human impacts of the earthquake as experienced on the ground.
Developed in the 1970s. An earthquake produces many types of waves, which radiate from its epicenter and move with a wide variety of frequencies. Compared to the Richter scale, the moment magnitude scale can account for more types of these waves, and at more frequencies. It is thus better able to estimate the total energy of earthquakes, and can also relate these observations to the physical features of a fault.
Mercalli Scale
A behavioral type classification of the resulting damage caused by earthquakes. It helps draw picture of the impacts along a transect from the epicenter. Rather than follow abstract logarithmic scale it describes the physical and human impacts of the earthquake as experienced on the ground.
Duration and speed of onset
The actual duration of an earthquake depends mainly on the physical conditions around the quake and your location.
In general, the greater the length of the fault, the bigger the earthquake, and the longer the duration of the quake. For example, the magnitude 7.8 quake that occurred January 9, 1857, at Fort Tejon, California, was generated by a 224 mile (360 kilometer) fault and lasted a record time in the United States—about 130 seconds. The famous April 18, 1906, San Francisco earthquake lasted for 110 seconds; the fault line there is about 250 miles (400 kilometers) long. But this rule is not ironclad: The Loma Prieta, California, quake on October 17, 1989, lasted 7 seconds from a fault 25 miles (40 kilometers) long; the January 17, 1994, Northridge, California, quake also lasted 7 seconds and was caused by a 9-mile (14-kilometer) fault.
Other factors are important to a quake’s duration: The amount of time you shake depends on how far you are from the epicenter, the magnitude of the earthquake, and the type of rock under your feet. For example, if you are close to the epicenter you will experience a longer shaking; and the ground will usually shake longer for higher magnitude quakes (seconds for small quakes, close to a minute for major quakes). The type of rock is important, too. If you are on sand, the shaking will last almost three times as long as if you stood on a stable bedrock such as granite.
Earthquake early warning systems do not predict earthquakes but provide some limited warning of their effects. The maximum warning time is very short - maximum a few minutes.
In general, the greater the length of the fault, the bigger the earthquake, and the longer the duration of the quake. For example, the magnitude 7.8 quake that occurred January 9, 1857, at Fort Tejon, California, was generated by a 224 mile (360 kilometer) fault and lasted a record time in the United States—about 130 seconds. The famous April 18, 1906, San Francisco earthquake lasted for 110 seconds; the fault line there is about 250 miles (400 kilometers) long. But this rule is not ironclad: The Loma Prieta, California, quake on October 17, 1989, lasted 7 seconds from a fault 25 miles (40 kilometers) long; the January 17, 1994, Northridge, California, quake also lasted 7 seconds and was caused by a 9-mile (14-kilometer) fault.
Other factors are important to a quake’s duration: The amount of time you shake depends on how far you are from the epicenter, the magnitude of the earthquake, and the type of rock under your feet. For example, if you are close to the epicenter you will experience a longer shaking; and the ground will usually shake longer for higher magnitude quakes (seconds for small quakes, close to a minute for major quakes). The type of rock is important, too. If you are on sand, the shaking will last almost three times as long as if you stood on a stable bedrock such as granite.
Earthquake early warning systems do not predict earthquakes but provide some limited warning of their effects. The maximum warning time is very short - maximum a few minutes.
Earthquake impacts
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Factors Affecting the Impact of Earthquakes:
Depth: If the hypocentre of an earthquake is close to the surface then it is more likely to cause greater damage than a deep earthquake. Duration: A longer earthquake is likely to cause greater damage than an earthquake that lasts only a few seconds. Magnitude: Obviously a stronger earthquake is going to have a greater impact than a weaker one. Time of Day: Time of day can be important. If people are sleeping and get trapped in their beds more people can be killed. In Japan an earthquake that struck while people were cooking their evening dinner caused widespread secondary hazards (fire) that caused more deaths. Epicentre Location: If the epicentre of an earthquake is an uninhabited region it is going to have a lesser effect than one under a densely populated city. Geology: If an earthquake occurs in solid bedrock it is likely to cause less damage than one centred below an alluvial floodplain which may lead to liquefaction. Economic Development (buildings, planning, preparedness): Generally speak more developed countries have better zonal planning, building codes and preparedness mean the effects of the earthquake are less. |
These articles will help you with your essay writing. Read them through them and highlight important information.
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Volcanoes
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Volcanic Distribution
Magnitude
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The Volcanic Explosivity Index (VEI)
Is a relative measure of the explosiveness of volcanic eruptions. It was devised by Chris Newhall of the United States Geological Survey and Stephen Self at the University of Hawaii in 1982. Volume of products, eruption cloud height, and qualitative observations (using terms ranging from "gentle" to "mega-colossal") are used to determine the explosivity value. The scale is open-ended with the largest volcanoes in history given magnitude 8. A value of 0 is given for non-explosive eruptions, defined as less than 10,000 m3 (350,000 cu ft) of tephra ejected; and 8 representing a mega-colossal explosive eruption that can eject 1.0×1012 m3 (240 cubic miles) of tephra and have a cloud column height of over 20 km (12 mi). The scale is logarithmic, with each interval on the scale representing a tenfold increase in observed ejecta criteria, with the exception of between VEI 0, VEI 1 and VEI 2. |
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The apparent volume of each bubble is linearly proportional to the volume of tephra ejected, colour-coded by time of eruption as in the legend. Pink lines denote convergent boundaries, blue lines denote divergent boundaries and yellow spots denote hotspots.
Volcanic Hazards
| Volcanic Hazards factsheet |
Predicting Volcanoes
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Can we predict when a volcano will erupt?
Scientists can often find clues about past eruptions by studying the deposits left behind. Areas affected by lava flows, debris flows, tephra, or pyroclastic flows can be mapped, making disaster planning more effective. In addition to this type of long-range forecasting, scientists are becoming more and more skilled at spotting the warning signs of an eruption.
Warning Signs
Before an eruption, magma moves into the area beneath the volcano and collects in a magma chamber, or reservoir. As it comes closer to the surface, the magma releases gases. These events can offer valuable clues about the likelihood of an eruption. For example, the movement of magma produces small earthquakes and vibrations (seismicity). Magma gathering in a chamber causes slight swelling of the volcano's slopes. Gases released near the volcano can be measured for changes in quantity and makeup.
Monitoring Methods
A number of tools can be used to record these warning signs. Seismographs can detect small earthquakes, while tiltmeters and geodimeters can measure the subtle swelling of a volcano. Correlation spectrometers (COSPECS) can measure amounts of sulfur dioxide--a telltale gas that is released in increasing quantities before an eruption. Using these and other tools, it's possible to closely monitor activity at an awakening volcano.
The Problem of Prediction
Volcanologists are becoming very skilled at predicting the likelihood of an eruption. Still, a number of barriers remain. It's very difficult to pinpoint exactly when an eruption will happen. Often, moving magma doesn't result in an eruption, but instead cools below the surface. Monitoring potential eruptions is expensive. With many volcanoes erupting only every few hundred or thousand years, it's not possible to monitor every site. Volcanic eruptions don't occur without warning, however. If we set up monitoring devices, we should not be caught off guard by disastrous eruptions.
Scientists can often find clues about past eruptions by studying the deposits left behind. Areas affected by lava flows, debris flows, tephra, or pyroclastic flows can be mapped, making disaster planning more effective. In addition to this type of long-range forecasting, scientists are becoming more and more skilled at spotting the warning signs of an eruption.
Warning Signs
Before an eruption, magma moves into the area beneath the volcano and collects in a magma chamber, or reservoir. As it comes closer to the surface, the magma releases gases. These events can offer valuable clues about the likelihood of an eruption. For example, the movement of magma produces small earthquakes and vibrations (seismicity). Magma gathering in a chamber causes slight swelling of the volcano's slopes. Gases released near the volcano can be measured for changes in quantity and makeup.
Monitoring Methods
A number of tools can be used to record these warning signs. Seismographs can detect small earthquakes, while tiltmeters and geodimeters can measure the subtle swelling of a volcano. Correlation spectrometers (COSPECS) can measure amounts of sulfur dioxide--a telltale gas that is released in increasing quantities before an eruption. Using these and other tools, it's possible to closely monitor activity at an awakening volcano.
The Problem of Prediction
Volcanologists are becoming very skilled at predicting the likelihood of an eruption. Still, a number of barriers remain. It's very difficult to pinpoint exactly when an eruption will happen. Often, moving magma doesn't result in an eruption, but instead cools below the surface. Monitoring potential eruptions is expensive. With many volcanoes erupting only every few hundred or thousand years, it's not possible to monitor every site. Volcanic eruptions don't occur without warning, however. If we set up monitoring devices, we should not be caught off guard by disastrous eruptions.
Frequency
Extended Reading
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| Why Are Volcanoes Rarely Big Killers? |
Mass Movements - Landslides -Avalanches
A landslide is a mass movement of material, such as rock, earth or debris, down the slope of a hill or cliff. They can happen suddenly or move slowly over long periods of time. Landslides are classified by their type of movement. The four main types of movement are:Landslides can be classified as just one of these movements or, more commonly, can be a mixture of several.
Like sand sliding off a tipper truck, slopes eventually fail because they become too steep to hold onto their load. A landslide may occur because the strength of the material is weakened. This reduces the power of the 'glue' that cements the rock or soil grains together. Located on a slope, the rock is then no longer strong enough to resist the forces of gravity acting upon it.
Several factors can increase a slopes susceptibility to a landslide event:
Like sand sliding off a tipper truck, slopes eventually fail because they become too steep to hold onto their load. A landslide may occur because the strength of the material is weakened. This reduces the power of the 'glue' that cements the rock or soil grains together. Located on a slope, the rock is then no longer strong enough to resist the forces of gravity acting upon it.
Several factors can increase a slopes susceptibility to a landslide event:
- water (rainfall or the movement of the sea) — this acts as a grease to the material increasing the likelihood that it will slip and also adds extra weight to the rock
- erosion processes — such as coastal erosion and river erosion
- steepness of slope
- type of 'rocks' — soft rock such as mudstone or hard rock such as limestone
- shape of the rock 'grains'
- jointing and orientation of bedding planes
- arrangement of the rock layers
- weathering processes — for example freeze-thaw reduces the stickiness (cohesion) between the rock grains.
- lack of vegetation which would help bind material together
- flooding
- volcanoes and earthquake activity nearby
- man's activity — mining, traffic vibrations or urbanisation which changes surface water drainage patterns
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An avalanche is a rapid flow of snow down a hill or mountainside. Although avalanches can occur on any slope given the right conditions, certain times of the year and certain locations are naturally more dangerous than others. Wintertime, particularly from December to April, is when most avalanches tend to happen. However, avalanche fatalities have been recorded for every month of the year.
All that is necessary for an avalanche is a mass of snow and a slope for it to slide down. For example, have you ever noticed the layer of snow on a car windshield after a snowfall? While the temperature remains low, the snow sticks to the surface and does not slide off. After the temperature increases, however, the snow will sluff, or slide, down the front of the windshield, often in small slabs. This is an avalanche on a miniature scale.
Of course, mountain avalanches are much larger and the conditions that cause them are more complex. A large avalanche in North America might release 230,000 cubic meters (300,000 cubic yards) of snow. That is the equivalent of 20 football fields filled 3 meters (10 feet) deep with snow. However, such large avalanches are often naturally released, when the snowpack becomes unstable and layers of snow begin to fail. Skiers and recreationalists usually trigger smaller, but often more deadly avalanches.
An avalanche has three main parts. The starting zone is the most volatile area of a slope, where unstable snow can fracture from the surrounding snow cover and begin to slide. Typical starting zones are higher up on slopes. However, given the right conditions, snow can fracture at any point on the slope.
The avalanche track is the path or channel that an avalanche follows as it goes downhill. Large vertical swaths of trees missing from a slope or chute-like clearings are often signs that large avalanches run frequently there, creating their own tracks. There may also be a large pile-up of snow and debris at the bottom of the slope, indicating that avalanches have run.
The runout zone is where the snow and debris finally come to a stop. Similarly, this is also the location of the deposition zone, where the snow and debris pile the highest.
Several factors may affect the likelihood of an avalanche, including weather, temperature, slope steepness, slope orientation (whether the slope is facing north or south), wind direction, terrain, vegetation, and general snowpack conditions. Different combinations of these factors can create low, moderate, or extreme avalanche conditions. Some of these conditions, such as temperature and snowpack, can change on a daily or hourly basis.
All that is necessary for an avalanche is a mass of snow and a slope for it to slide down. For example, have you ever noticed the layer of snow on a car windshield after a snowfall? While the temperature remains low, the snow sticks to the surface and does not slide off. After the temperature increases, however, the snow will sluff, or slide, down the front of the windshield, often in small slabs. This is an avalanche on a miniature scale.
Of course, mountain avalanches are much larger and the conditions that cause them are more complex. A large avalanche in North America might release 230,000 cubic meters (300,000 cubic yards) of snow. That is the equivalent of 20 football fields filled 3 meters (10 feet) deep with snow. However, such large avalanches are often naturally released, when the snowpack becomes unstable and layers of snow begin to fail. Skiers and recreationalists usually trigger smaller, but often more deadly avalanches.
An avalanche has three main parts. The starting zone is the most volatile area of a slope, where unstable snow can fracture from the surrounding snow cover and begin to slide. Typical starting zones are higher up on slopes. However, given the right conditions, snow can fracture at any point on the slope.
The avalanche track is the path or channel that an avalanche follows as it goes downhill. Large vertical swaths of trees missing from a slope or chute-like clearings are often signs that large avalanches run frequently there, creating their own tracks. There may also be a large pile-up of snow and debris at the bottom of the slope, indicating that avalanches have run.
The runout zone is where the snow and debris finally come to a stop. Similarly, this is also the location of the deposition zone, where the snow and debris pile the highest.
Several factors may affect the likelihood of an avalanche, including weather, temperature, slope steepness, slope orientation (whether the slope is facing north or south), wind direction, terrain, vegetation, and general snowpack conditions. Different combinations of these factors can create low, moderate, or extreme avalanche conditions. Some of these conditions, such as temperature and snowpack, can change on a daily or hourly basis.
| Avalanches |
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ENSO - el Nino Southern Oscilation
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Using the slide share and resources below, draw and explain ENSO events and discuss what the impacts can be on the planet.
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Read through the El Nino Geofile and create a 1 page summary of:
How can El Nino impact Global Weather Patterns? ! Make sure you include named places and actual evidence ! |
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Hydro-meteorological hazards
Drought
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Palmer Drought Index
The Palmer Drought Index, sometimes called the Palmer Drought Severity Index and often abbreviated PDSI, is a measurement of dryness based on recent precipitation and temperature.
Complete the hazard summary sheet
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Predictability, Frequency and duration
Studies conducted over the past century have shown that meteorological drought is never the result of a single cause. It is the result of many causes. Scientists don’t know how to predict drought a month or more in advance for most locations. Predicting drought depends on the ability to forecast two fundamental meteorological surface parameters, precipitation and temperature. From the historical record we know that climate is inherently variable. We also know that anomalies of precipitation and temperature may last from several months to several decades. How long they last depends on air–sea interactions, soil moisture and land surface processes, topography, internal dynamics, and the accumulated influence of dynamically unstable synoptic weather systems at the global scale. Meteorologists have made significant advances in understanding the climate system. It may now be possible to predict certain climatic conditions associated with ENSO (El Nino) events more than a year in advance. For those regions whose climate is greatly influenced by ENSO events meteorological forecasts can reduce risks in those economic sectors (mainly agriculture) most sensitive to climate variability and, particularly, extreme events such as drought. | ||
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Effects
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Predicting Drought
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Droughts: Sahel & California
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Tropical Storms: Hurricanes, Typhoons & Cyclones
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Hurricanes: A hurricane is a large low pressure system characterised by high winds and heavy rain. Hurricanes are also known as typhoons in East and South-east Asia and cyclones around the Indian Ocean. To be classified as a hurricane, winds must exceed 119km/hr (74 mph). Small low pressure systems are called tropical storms (63-118km/hr) and tropical depressions (0-62km/hr).
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| hurricanes.pdf |
Spatial extent
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Tropical cyclones are like giant engines that use warm, moist air as fuel. That is why they form only over warm ocean waters near the equator. The warm, moist air over the ocean rises upward from near the surface. Because this air moves up and away from the surface, there is less air left near the surface. Another way to say the same thing is that the warm air rises, causing an area of lower air pressure below.
Air from surrounding areas with higher air pressure pushes in to the low pressure area. Then that "new" air becomes warm and moist and rises, too. As the warm air continues to rise, the surrounding air swirls in to take its place. As the warmed, moist air rises and cools off, the water in the air forms clouds. The whole system of clouds and wind spins and grows, fed by the ocean's heat and water evaporating from the surface. Storms that form north of the equator spin counterclockwise. Storms south of the equator spin clockwise. This difference is because of Earth's rotation on its axis. As the storm system rotates faster and faster, an eye forms in the center. It is very calm and clear in the eye, with very low air pressure. Higher pressure air from above flows down into the eye When the winds in the rotating storm reach 39 mph, the storm is called a "tropical storm." And when the wind speeds reach 74 mph, the storm is officially a "tropical cyclone," or hurricane. Tropical cyclones usually weaken when they hit land, because they are no longer being "fed" by the energy from the warm ocean waters. However, they often move far inland, dumping many inches of rain and causing lots of wind damage before they die out completely. | ||
Predictability
| 162_huricanes-predictable_hazard.pdf |
Frequency and Magnitude
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Hurricanes are normally measured by using the Saffir-Simpson Hurricane Scale developed by the National Oceanic and Atmospheric Administration. Hurricanes are measured on a scale of 1-5 depending on their wind speed and storm surge.
However, it must be noted that category five storms don't always cause the most damage. The amount of damage caused by hurricanes can depend on a number of factors including:
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Scientists disagree on whether or not tropical storm activity has increased over recent years. Many scientist believe that global warming has caused larger and more frequent storm.
Speed of Onset & Effects
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Hurricane Katrina and Cyclone Nargis
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Hazard Mapping
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Using the world map below (print out) explore and mark in the areas that exhibit the following hazards:
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Hazard Hotspots
Disaster hotspots are vulnerable places at risk from two or more hazards
Using pages 24 to 29 in your Oxford AS Geography textbook create 2 factfile case studies on Hazard Hotspots:
I want you to create this using PowerPoint but to then record this as a video using the narration feature to explain in words each of your points. Try to avoid just reading the slide instead expand on your reasoning. [20 marks]
10 marks - quality of information
5 marks - presentation
5 marks - detailed explanation
- The Philippines
- California
- Locate the area.
- Explain why they are a hazard hotspot - create an overview of the types of hazards they experience.
- Try to give one real life example of each of the hazards including basic data eg. deaths, damage etc.
I want you to create this using PowerPoint but to then record this as a video using the narration feature to explain in words each of your points. Try to avoid just reading the slide instead expand on your reasoning. [20 marks]
10 marks - quality of information
5 marks - presentation
5 marks - detailed explanation
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Mega Disasters
Mega Disasters: Disasters that have an unusually large human and economic impact that affect a large geographical area (normally two or more countries). For example certain Tsunamis, earthquakes, tropical storms or regional drought.
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For the 2004 Indian Ocean Tsunami - Play from 24m 20secs
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| Asian Tsunami 2004 |
Create a mind map of the implications of a Mega Disaster. Do not just focus on tsunamis. Discuss. |
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Essay Planning and Writing
- Assess why some people are more vulnerable to hazards than others [20 marks]
- Death tolls from natural hazards are declining but the economic cost is rising, discuss [20 marks]
Use the stimulus material below to plan and answer question 2:
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The Causes of Climate Change
The global energy budget
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The main greenhouse gases
Evidence suggesting Global Warming is a long term process
| global_warming_fact_fiction_and_myth.pdf |
Use pages 32 to 33 in you AS Geography for Edexcel Text book
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Changes in solar outputs
Milankovitch Cycles
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Volcanic Emissions
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How do we know past temperatures?
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Information about past climate is obtained from piecing evidence together from various sources.
These include:
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The Effects of Climate Change
| geofile_616_climate_change_and_vulnerable_areas.pdf |
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Using the YouTube documentary and the documents below create a factfile of the impacts that Climate change has on our planet. Remember to note down critical information as well so as to use it in evaluative essays.
Essay
Explain the impacts that climate change can have on the world. [10]
Dealing with Climate change
There are two main approaches that the world can take to deal with climate change:
- Mitigation: refers to the policies which are meant to delay, reduce or prevent climate changes - cutting C02 emissions by instituting congestion charges or carbon sinks.
- Adaption: refers to the policies which are designed to reduce the existing impacts of climate change - flood protection and coastal erosion.
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| Responses to climate change |
Using pages 45-59 from AS Geography for Edexcel examine the methods of combating climate change.
