TECHTONIC HAZARDS

Question 1

Explain two strategies used to modify tectonic hazard events?

Answer 1

1. Ash resistant roofs which are stronger so can cope with the weight of heavy ash fall so less reduces deaths from collapsing building
2. Prediction and warning systems that already such as DART and the PTWC so people have time to evacuate

Question 2

Explain how plate tech tonic theory is used to explain plate movements

Answer 2

Movements of the plates that float in the aesthenosphere which make up the earth’s crust.

Mantle convection is where heat produced by the radio active decay of elements in m the Earth’s core along with heat left over from the Earth’s formation heats up the lower mantle creating convection currents which move
plates by frictional drag.

It can be explained by ridge push where new oceanic crust formed at plate boundaries see huge mantle plumes push up the lithosphere causing it to have a slope. This causes plates to slide downwards forcing them part in opposite directions or break apart which can result in sea floor spreading or rifting.

Slab pull occurs when magma rise and cools over thousands of years so the older more dense oceanic crust sinks into the mantle causing plates to drag the warmer less dense parts of the plate into the asthenosphere. This subducted crust melts into magma at destructive plate boundaries in the Benioff zone which then rises.

Question 3

Assess whether area extent is the most important factor that determines the impact of volcanic eruptions

Answer 3

1. Areal extent is an important factor as the location of a disaster can have impacts on a global scale in social and economic terms. The volcanic eruption in Iceland 2010 had serious global impacts with the thick cloud of ash resulting in not just the poisoning or water sources and destruction of agricultural land in local terms. But also leading to a halt in passenger and freight traffic throughout Europe with large airspaces closed down with over 100,00 flights cancelled and airlines losing a combined revenue of £130m per day. Furthermore Europe’s biggest tourism businesses lost between £5 million and £6 million per day with even in developing countries such as Kenya the economy lost £2.8 billion because of flights to Europe being cancelled as fresh flowers and food were ruined couldn’t be sold.
2. There are many other factors shown in hazed profiles which also dictate the impacts of a volcanic eruption such as the speed of onset and the magnitude of the disaster. If a eruption had a slow speed of onset and monitoring and preparation surgeries had been put in place such as seismometers and volume of volcanic gases in the air, warnings would be possible decreasing the loss of life in social terms but will have no effect on the economic damages and the negative multiple effect that will follow. The number of deaths from Mount Etna which was highly monitored was only 19 and those were due to people being inside the exclusion zone.

Overall it depends on how we judge the impact of it is based on social losses or economic impact and whether we are judging on the effects on a local or global scale, Countries which are less connected than others due to economic reasons will have a lower global impact on supply chains but the local impacts will be greater such as in the Phillipenes after the eruption of Mount Pinatubo which struggled to recover due to poor economy and lack of resources which hindered its ability to recover.

Question 4

Explain two process of weathering on a coastline

Answer 4

1. Mechanical weathering it’s pressure on cracks/ fractures in the rock and processes such as free thaw widen bedding plains in the rock surface leading to collapse
2. Chemical weathering where rock such as limestone is dissolved as it reacts with oxygen in the air or acidic water

Question 5

Explain the characteristics of coastal plains and rocky coasts differ

Answer 5

Coast plains:
Are sandy and are found in areas of low relief in a low energy environment due to coast processes. For examples beaches which are low lying and extend for miles as low energy environment allows for build up of sediment deposition from constructive waves solidified by vegetation such as marram grass.

Rocky Coasts:
Are characterised by erosional marine processes on resistant rock resulting in high relief coastlines characterised by steep cliffs and wave cut platforms as there is little protection from the sea so processes such as hydraulic action attack more resistant rocks like granite and metamorphic rocks. Rocky coasts in disconcordant coastline also create structures such as bays and headlands such as Swanage Bay.

Question 6

What is the purpose of a Chi-Squared Test?

Answer 6

There are categories of data and the test establishes whether there is an uneven distribution pattern amongst categories

Question 7

Explain two primary school methods that can be used to extend field work investigations

Answer 7

1. Comparing modern photographs of my old maps and photos to see changes over time
2. Measure sediment size to identify whether material size changes along the beach
3. Beach profiling which shows how beach size/ relief changes and if longshore drift has had an impact
4. Measure wave frequency to find wave type to establish if constructive waves are building up the beach

Question 8

Explain two characteristics of volcanic hotspots

Answer 8

Volcanoes are formed and live away because the chronic plates move over the hot spot which remains stationary

Large shield volcanoes are formed because as lava has a low viscosity so spreads before cooling

Question 9

Explain why volcanic eruptions vary in thier magnitude

Answer 9

The magnitude to volcanoes is measured using the Volcanic Explosivity Index which measure factors including volume of erupted material and duration of explosion.

Variation is due to the plate boundary on which the volcano is found where destructive plate boundaries where oceanic plate descends into the mantle and magma rises lead to strato volcanoes which are are likely to have a higher magnitude. This is because volcanoes like Mount Etna produce andesitic and rhyolitic magma with a higher silica content and high viscosity resulting higher in more violent eruptions as gas bubbles cannot escape and build up over time. Volcanoes on constructive plate boundaries are lower in magnitude as volcanoes produce basaltic lava which has a low silica content and low viscosity so gas bubbles can escape more easily resulting in less explosive eruptions

The amount of dissolved gas is the biggest factor as andesitic magma traps gas bubbles unlike basaltic magma which cannot escape some the gases are under immense heat and pressure leading to explosive eruptions such as Mount Pinatubo with lava bombs and ash clouds

Question 10

Asses the effectiveness of prediction and forecasting in the management of tech tonic hazards

Answer 10

Management of tech tonic hazards are displayed on models such as the Park model which shows the decisions and measure out in place before, immediately after and long term effects. The effectiveness can be judged by a reduction in the magnitude of the event, reduced vulnerability and reduced loss of life depending on whether you are judging on social or economic basis.

On the one hand prediction and forecasting are effective as they allow government to start disaster planning in areas such as Nepal where there is a high frequency of high magnitude events. Scientists can monitor using pressuremeters and seisometers to divert lava flows such as was done at Mount Etna and allow people to move away from danger zones by using land use exclusion zones and providing evacuation routes and education reducing loss of life in social terms. It can also help in economic terms to reduce damages to property and infrastructure by diverting lava flows or building higher sea walls for tsunamis such as in Tohoku Japan.

On the other hand they are not effective as accurate predictions can only be made in the short term such as tremors and long term prediction devices and methods are still in their infancy so the magnitude of some hazards cannot be predicted so building defenses such as sea walls may be a useless seen in Tohoku where the 10m sea wall was effectively 9m due to subsidence so the cost of planning was prohibitive. Multiple hazard events can sometimes interact in unpredictable ways such as typhoon after Mount Pinatubo eruption.

The type of governance and the attitude and ability to communicate with the local people influences the effectiveness. if people have a fatalistic religious approach than the effectiveness is constrained by the decisions people make. The effect on humans and thier actions are more easy to control so focusing on latter stages of the Hazard Response cycle such as Mitigation and Preparedness are likely to have the biggest impact building earthquake proof buildings with stabilisers or implementing land uses zones and exclusion zones are the most effective.

Question 11

How might a rise in sea level affect coastal landscapes?

Answer 11

Higher sea level might cause flooding which might breach sea defences and cause damage to ecosystems such as salt marshes and farms near the coast

Question 12

Why are some locations at risk from coastal flooding?

Answer 12

Low lying coastal location such as Bangladesh which lie less than 5m above sea level will lose flat land to sea level as water floods land

Funneledtopography such as in the Bay of Bengal which has many river flowing through it will concentrate the effects of locally increased sea level and flooding risk

Question 13

Explain how vegetation helps to stabilise sandy coastlines

Answer 13

Pioneer plants colonise areas and plant succession over time adds moisture and stabilises lose sand which allows for more plants to grow stabling themselves. Furthermore salt marshes and spits can create low energy environments behind them by acting as buffer zones and taking the impact of storms and strong winds.

Plants such as Marram grass with deep root networks in bare sand can trap sand and prevent it being blown away allowing dunes to build up over time encouraging further sand deposition as areas of protected beach are made.
Sand can become trapped around obstacles to form dunes which allows more sand to collect and provide conditions for pioneer plants to colonise dunes and hold the sand together.

Question 14

Describe the main differences between constructive and destructive waves

Answer 14

Constructive waves are low energy depositional waves with a low wave height of less than 1 metre and a long wavelength up to 100m. They have a low wave frequency of about 6-9 waves per minute which also means their swash is stronger than their backwash. Constructive waves create a gentle low gradient beach profile as a strong swash pushes sediment up the beach and a weaker backwash is unable to transport sediment off the beach so it’s deposited as berms along the beach. The gentle gradient indicates a shallow nearshore which forms constructive waves as friction slows down the wave and causes it to break early leading to a weaker backwash.

Destructive waves have are high energy erosional waves with a large number ace height of more than 1 metre and short wavelength of around 20 metres. They have a high wave frequency of around 13-15 per minute which also means their backwash is greater than their swash. They create a steep gradient beach profile as string backwash carries sediment back down the beach as the weaker backwash is unable to carry the sediment far so sediment is deposited as an offshore ridge. The steep gradient indicates a deep nearshore zone so less energy is lost through friction and causes it to break further up the beach.

Question 15

Referring to a named stretch of coastline, explain how marine, physical and human processes interact to produce a variety of landforms

Answer 15

One area where there are multiple landforms is the Holderness coast in Yorkshire where processes such as longshore drift and storm surges interact with the concordant coastline resulting in erosional and depositional landforms such as spits and headlands.

One landform is Spurn Head spit which is found at Spurn Point which is a depositional landform created by wave action. Dominant waves from the north east erode sediment from the beaches which is then carried southwards by longshore drift. The sediment is then deposited when it reaches the low energy environment created by tides and the Humber estuary where graded deposition occurs allowing the sediment to collect forming a large recurved spit. Processes such as coastal management as Hornsea and Mappletion implementing groynes leads to terminal groyne sediment starving the rest of the sediment cell and the spit of sediment and climate change lead to eustatic rise resulting in coastal flooding and increases erosion.

Another erosional landform which has been created is Flamborough head where the concordant nature of the coastline has led to the formation of classic arch, stack and wave cut platform features. The lithology of the rock which is made of resistant rock and the horizontal bedding planes has allowed for these landforms to form. Erosional processes such as hydraulic action where air is trapped in faults in the rock and abrasion where sediment is hurled against the rock especially in stormy conditions where more destructive waves are created allows for faults to be exploited to form notches which are widened out and eventually collapse. Human activity at the top of the headland also leads to rock falls as material is broken off and is then hurled back at the cliffs and heavy periods of rainfall lead to slumping as the headland becomes saturated with water increasing the formation erosional landforms.

Other examples include the Holderness cliffs as the easily erodible boulder clay cloud facing marine erosion and cloud face processes such as slumping due to heavy rainfall create sloping cliffs due to slip planes in the cliffs.

Question 16

Outline two processes by which coastlines are eroded

Answer 16

Hydraulic action where cliffs may contain lines of weakness such as cracks or fault in which air can be trapped when water is hurled against it which causes the pressure to increase and leads to weakening or breaking of the rock face

Chemical weathering where rocks such as limestone react with the carbon dioxide in the air causing it to dissolve creating lines of weaknesses and breaking the rock down

Question 17

Briefly outline the key stages in the formation of a stump

Answer 17

Weathering and marine processes such as hydraulic action where air is compressed within cracks within the rock and an increase in pressure weakens and break away at the rock along with processes such as abrasion where sediment is hurled at the rock breaking pieces off. A cave is formed when a crack or fracture is widened until
It becomes a hollow opening in the cliff face. An arch is formed when the cave breaks through to the other side of the rock forming an arch which will get bigger until it collapses due to gravity due to lack of support. This leaves a headland on one side and a stack on the other which will continue to be attacked at the base in the same way a wave cut notch if formed which weakens its structure eventually collapsing due to gravity forming a stump this process is seen at old Harry’s rocks in the aisle of Purbeck

Question 18

Explain how urbanisation at the coast impacts on coastal processes?

Answer 18

In developed countries such as the UK urbanisation at the coast can have a negative effect on coastal process. Artificial channelisation of rivers can speed up river flow and also reduce sediment available to beaches starving coasts of sediment. Rates of beach erosion are increases as seen at Barton on Sea with the cliff being eroded at 2m a year which may require human intervention in the form of hard engineering such as groynes which can then cause problems further down the coast within the same sediment cell as wave energy is concentrated further along the coast.

In less developed countries such as Bangladesh the Sundarbarbans are are being destroyed with 25% lost to erosion in the last thirty years. Mangroves provide protection against storm surges and cyclones with 100m of mangrove forest able to reduce wave energy by up to 40% but due to pressure for land space they are being destroyed to make for tourism, local industry such as shrimp and rice farming or for housing.Mangroves are an excellent method of coastal management as they can also keep up with global sea level rises of up to eight times the current rate. They trap sediment leading to accretion on the coastline, helping protect communities from the potential impacts of climate change. This will
Increase the rate of erosion at the coastline as well as leave the coastline more vulnerable to hazards such as cyclones and tsunamis as depositional landforms are destroyed such as Spurn Head spit which was largely damaged due to a storm surge.

Question 19

How does longshore drift work?

Answer 19

Waves hit the beach at an angle in the direction of prevailing wind and from the direction of maximum fetch and carry sediment up the beach in its swash which is then carried back down the beach in the backwash. This causes individual particles to be moved along the beach in a zig zag pattern until it reaches a low energy area.

Question 20

Why do some spits form a curved end?

Answer 20

Spits form a curved end as they grow in the direction of dominant fetch or prevailing wind. However when they reach an area where the frequency of the 2nd most dominant fetch and wind direction is higher than that of the most dominant deposition will occur differently forming a curved end seen at Spurn Head spit which has a curved end due to an area of lower energy created by the presence of a river flowing into the sea.

Question 21

For any names stretch or coastline evaluate the success of costal management strategies adopted

Answer 21

One area which has experienced large rates of erosion is the Holderness coastline in Yorkshire where over twenty nine villages have disappeared due to erosion and rising sea levels, this problem continues to grow as population grows and economic development and recreation grows.

One village which has had hard engineering strategies put in place after a Cost Benefit Analysis was carried out to determine the costs of protection vs the value of the protected land was found to be greater was Hornsea. A hold the the line strategy was employed where new defences were built in 1994 including the repair and replacement of 19 groynes, undergoing sea walls as well as building a flood wall and rip rap which had a total cost of £5.2million. This was mainly due to the tourist value of the location and the design was specifically tailored to avoid damage to the beach front or deter holiday makers and commercial operators. The scheme was widely seen as successful as it reduces erosion to the south and even allowed for for new housings to be built close to the coast.

Another village that had hard engineering strategies implemented was Mappleton further down the coast which was protected with 2 rock armour groynes and rip rap constructed to counteract wave erosion in storm and spring tide conditions as well as regrading of the boulder clay cliffs to prevent landslides and provide new road access. The village is protected at a coast of £2m despite being valued at £650,00 as the primary reason was to protect the B1242 road. In the short term the management was successful as the road was protected and erosion slowed by a large amount but in the long term there is still a risk of outflanking as erosion is getting behind where coastal defences stop leading to rapid erosion inland and defences being undermined. It has also led to South Cowdon south of Mappleton seeing alarming rates of erosion and the regraded cliffs have shown signs of potential landslides and slumping.

Other areas include Barmston which had a do nothing strategy implemented as a cost benefit analysis indicates that the coast is installing defences wasnt worthwhile since the population was low at only 200 which means the current erosion will continue.

Overall the strategies implemented are successful in the short term in protecting the coastline and managing the economic and social benefits of protecting the coastline with tourist attractions which is a main economic revenue. However in the long term rising sea levels and eustatic rise will lead to the undermining of some defences and terminal groyne syndrome will increase erosion rates at different areas decreasing their success

Question 22

Explain the difference between isostatic and eustatic sea level change

Answer 22

Eustatic sea level change is a global change in sea level due to steric changes ie leading to melting or formation of glaciers. Whereas isostatic change is a local change in sea level due to changes in the height of the land due to decompression leading to sea level decrease or compression leading to sea level rise.

Question 23

For a named feature of coastal submergence explain its formation and usefulness to man

Answer 23

Rias are drowned river valleys formed in the ice age when rivers still flowed they cut down the the new lower seas level. As long ice sheets and glaciers form, there is a eustatic fall in seas level as there is a negative change on n base level as the land is depressed by weight. As ice sheets melt and there is an eustatic rise in seas level there is a positive change in base level due to continued decline of glaciers and isostatic uplift of the land. The ria is wider at the mouth and narrows further inland as the river looses its ability to cut through.

Question 24

Define an emergent landform

Answer 24

Emergent landforms are produced by post glacial adjustment, parts of the littoral zone where eustatic fall or isostatic rise has exposed land once part of the sea bed or near sea level.

This includes a raised beach which a relict beach which is now above high tide level and has a flat surface covered by sand and rounded pebbles/ boulders vegetated with plant succession.

This includes a fossil cliff which is a steep slope found at the back of a raised beach exhibiting evidence of formation through marine erosion but now above high tide level containing wave cut notches, caves, arches. The episodic nature of isostatic recovery allows marine processes to erode cliffs and deposits beaches when sea levels are stable. A relatively rapid drop in sea level leaves relict coastline abandoned above high tide and some distance inland eg . The Isle of Arran has a raised beach 5m above current sea level with three different raised beaches.

Question 25

Using a named example explain the sediment cell concept

Answer 25

A sediment is cell is a linked system of sources transfers and sinks of sediment along a coastline. The England coastline is divided into 11 primary sediment cells with the boundaries formed by major headland or estuaries such as the Thames estuary. Sediment cell 2 from Flambourough Head to the Wash includes Spurn Head spit as a source. It operates in a closed system with no inputs from another or outputs of sediment to another cell and within a dynamic system because the sediment is constantly regenerated from the source region through coastal erosion processes such as hydraulic action and attrition, transported through the transfer region which are places where sediment is moving along shore through longshore drift and offshore currents and deposited in the sink region where depositional landforms are created such as beaches and spits and bars such as Spurn Head spit in the Flamborough Head coastline. Coastal erosion of the Flamborough Head cliff face produces sediment and other sediment enters from rivers, lagoons or offshore transport from other sediments. The equilibrium is dynamic because there’s a constant movement of sediment through the system. It maintains equilibrium through negative feedback when the change produced creates effects that operate to reduce against the original change eg when erosion leads to block fall mass movement the collapsed debris acts a barrier protecting the cliff base preventing erosion for a period of time.

Question 26

Explain two economic reasons why coastal recession is significant

Answer 26

Housing can be threatened by erosion creating insurance problem for homeowners as they are forced to move away and their house has minimal value so loss money

Businesses and tourism can be threatened and forced to fund relocation to a new area away from current customers

Question 27

Explain two parts of the Pressure/ Rlease Model

Answer 27

Root causes are background political/ economic causes which determines how much the government is able to support the needs of different groups in society

Dynamic pressures are local economic or political factors that can affect a community or organisation by creating unsafe conditions

Unsafe conditions are specific and people are vulnerable because of lack
of health and safety and poor infrastructure

Question 28

Asses the importance of governance is in determining risk after an earthquake..

Answer 28

I will be using the 2010 Haiti and 2015 Nepal earthquakes in developing countries and the Japan 2011 earthquake in a developed country to consider how important governance is in determining risk after an earthquake.

On the one hand governance is an important factor as for example in Haiti poor governance was made worse by the lost lives of 25% of government officials which resulted in a lack of coordination in the recovery response as aid charities were extremely disorganised with the British Red Cross not knowing where to use the money they had as they had no information on the disaster zones and the areas which were most badly affected so more people died trying to help others with no proper knowledge or equipment as aid couldn’t reach them in time. Poor governance also meant there was
a lack of building restrictions and government intervention to make and uphold laws so there was a large risk of buildings collapsing even after the earthquake had occurred with people killed by collapsing buildings once, they returned to salvage. This was also true in developing countries such as Japan were builders bribed corrupt officials to take shortcuts making buildings unsafe and causing destruction of over 5 million buildings leading to a greater loss of life which could have easily been prevented.

On the other hand difference in economic vulnerability and resilience also had a major impact with Haiti being the poorest country in the Western hemisphere so it had a lack of funds to recover and replace damaged infrastructure with the estimated total of damaged being 120% of its GDP at $8bn.
This meant by 2015 80000 Haitians were still living in temporary housing or camps leading to spread of diseases and illnesses due to lack of sanitation and medical supplies with 9000 people dying to cholera. The lack of GDP also meant a negative multiplier effect with many people losing their jobs and livelihoods so its GDP continues to fall, there was also a lack of education and knowledge about earthquakes with only 62% of adults being literate so more people died unlike in China which is much more developed and wealthier so there was a much more prepared healthcare system and better education so people knew what to do in the event of an earthquake.

Other factors including environmental vulnerability are also important as a more mountainous and steep topography such as in Nepal is also much more vulnerable to secondary hazards such as landslides and mass flow which will result in a greater amount of deaths and also In Haiti where unconsolidated sediment particularly near the river basin means it is also at risk of landslides and lateral spreading.

Question 29

Global impacts of tech tonic hazards

Answer 29

Impacts of the EJF eruption in Iceland

Cloud of ash spread to the rest of Europe causing concerns about the possible harmful effects of ash
on aeroplane jet engines, large sections of European airspace closed down. Passenger and freight traffic throughout much of Europe ground to a halt which led to a drop in tourist numbers affected
Iceland’s economy as well as local people’s jobs and incomes with some 100,000 flights cancelled. The financial effects of such hazard were made worse by the fact that Iceland at the time was
experiencing recession and was in extreme financial trouble because of the collapse of its banking systems. The affected reconstruction of roads and services was expansive and expensive and was made by a negative multiplier effect that occurred due to a loss of Iceland primary sources of income
agriculture and tourism

There were also many environmental impacts with ash falls coating a large proportion of its agricultural land which were the main primary effects of the eruption. It also meant local water
supplies were also contaminated with fluoride form the ash making it undrinkable and poisonous to
wildlife and residents alike so people had to rely on supplies from aid agencies. Large amounts of
flood water were released from frozen glaciers flooding a large proportion of its major roads and infrastructure making it more difficult for aid to reach certain areas and had a negative effect on
agriculture and removal or volcanic debris and rebuilding.

Question 30

Causes of the 2011 Japanese Tohoku earthquake

Answer 30

Japan is located in one of the most active earthquake zones on earth. The Philippine plate and the Pacific plate are moving towards the much bigger continental Eurasian and North American plates. The movement can be up to around 8cm each year and this is a destructive plate margin where a subduction zone has formed. The thin, oceanic Pacific plate is being forced (sub-ducted) underneath the much thicker continental Eurasian plate. Frictional force has built up over time and when this overcame the resistance force large amounts of energy were released resulting in megathrusts and triggering tsunamis.

Over 15,000 people were injured and over 130,00 people were displaced. This was made worse by 800 earthquakes of magnitude 4.5 or more were recorded after the initial quake. Triggered tsunami up to 40m high that resulted in further live loss which caused destruction and pollution up to 6 miles inland. Land subsidence meant tsunamis walls weee rendered useless which had an economic cost of over $12bn with a total economic cost of over 235 billion dollars making it the most expensive natural disaster.

Question 31

Explain how some techtonic hazards occur away from plate boundaries

Answer 31

The main reason is that seismic waves can travel great distances and sometimes trigger techtonic hazards away from the plate boundary such as tsunamis which can be triggered by plate rebound at a boundary resulting in the waves travelling over 800km to hit coasts . Intra plate volcanoes can occur within a plate such as the Gujarat earthquake in 2001 due to faults and weaknesses within the plate and cause more damage as they are not seismically monitored or buildings specially designed. I trap late volcanic eruptions can also happen because of mantle plumes which melt the overlying crust so magma forces its way upwards. Successive oceanic volcanoes are formed as techtonic plates move over the hotspot which remains stationary such as the Haitian islands.

Question 32

Asses the view that tectonic hazards are causing affecting more people in the world but are causing fewer deaths tha in in the past

Answer 32

Tectonic hazards include volcanic eruption, earthquakes, tsunamis as well as hydrometerological hazards in multiple hazard zones. Disaster impacts is raised by unequal income and healthcare opportunities as well as poor governance and other geographical factors such as topography and can have regional or global significance because of economic and human impacts.

Question 33

Asses how the accuracy of prediction and forecasting depends on the type and location of tectonic hazards

Answer 33

Prediction and forecasting are part of the preparation and mitigation stage of the hazard cycle and will decrease the impact of tectonic hazards by increasing awareness and allowing people to evacuate

The accuracy of prediction and forecasting for volcanoes is measured using the Volcanic Explosivity Index which is based on the type of volcano and the height of ash plumes and material which erupts from it. Volcanic eruptions can be predicted more accurately than other hazards as they tend to have a longer speed of onset and changes in the volume of gas emitted and pressure changes are more easily recognisable as they are more obvious. Using the hazard model we can see that strato volcanoes tend to erupt more violently with andesitic fast flowing lava due to high silica content and the inability of gas to escape so changes in pressure and activity can be seen more quickly than with shield volcanoes.

Tsunamis are harder to predict as the tsunami waves have a short wave height and long wave length in open ocean so are hard to distinguish between normal waves. Tsunamis are predicted using DART technology which sends signals by surface buoys to the PWTC the Pacific Tsunami Warning centre if there is a change in pressure on the ocean floor twice in a 30 second interval. This means if the tsunami waves travel long distances they can be accurately predicted and prepared for compared to tsunami waves that form close to the shoreline.

Furthermore it also depends on the location of the hazard as HIC’s are more developed so are more likely to have more expensive and advanced prediction technology so are more likely to predict hazards such as tsunamis more accurately . They have more funding to have research and development teams to implement such technologies unlike LIC’s which will not have the same level of technology such as Haitis which is the poorest country in the Western Hemisphere so will be harder to accurately predict tsunamis and earthquakes.

Question 34

Suggest one way hazard management strategies may have affected the earthquake impacts in Japan

Answer 34

Building of earthquake proof buildings with stabilisers or reinforced corners means the buildings are less likely to collapse as a result of seismic waves and ground shaking decreasing the loss of life as less people are killed by collapsing buildings due to them collapsing in on themselves because of improved government regulations

Question 35

Explain two secondary hazards caused by earthquakes

Answer 35

Tsunamis caused by vertical water column displacement due to oceanic plate rebound which ripple outwards

Landslides in hen ground shaking destabilises material on slopes chasing it to slide and collapse

Question 36

Explain the tectonic hazards that may result from volcanic activity

Answer 36

Jokulhamps may occur when the volcano is beneath an ice cap when it erupts causing large amount of ice to melt and become large volumes of water which burst over the sides of the volcano and cause flooding of surrounding plains as the water travels large distance.
Lahars are also caused by the rain water mixing with ash on the sides of a volcano forming a flow of material across nearby land depositing a layer of ash upon farmland and villages. Ash itself can travel for hundreds of miles in the air carried by the wind and being deposited upon buildings causing them to collapse and contaminating water supplies and can also trigger thunderstorms due to electrostatic charging.

Question 37

Explain two coastal depositional processes

Answer 37

Graded deposition occurs when sediment suspended in solution reaches an area of low energy so larger sediment is deposited first as the waves lose energy

Longshore drift transports material eroded from a headland and redistributes it along the beach

Question 38

Suggest one reason why wave frequency may differ between two points

Answer 38

Point A is facing the prevailing wind direction so wind energy is higher so the longer fetch carries destructive waves
Point B is less exposed and is not facing the prevailing wind direction so the wind energy is lower so the headland protects the area.

Question 39

Explain the factors that create an erosional coastline

Answer 39

One major factor is the type of waves that reach the coastline. Destructive waves have a stronger backwash and weaker swash as they break later along the coastline closer to the shore due to the steep gradient of the coastline. They have a longer wave height and a high frequency of 8-10 waves a minute so transport sediment from the coast and deposit it elsewhere in offshore bars.

The lithology and characteristics of the rock is also an important factor as softer unconsolidated rock are vulnerable to erosional processes such as hydraulic action where air is compressed within faults in the rock exploiting and widening them. Igneous rocks have a stronger crystalline structure and are less susceptible to erosion compared to sedimentary rocks which will have faults and joints in the rock which can be exploited to form caves which are hollowed out to form arches which collapse due to gravity to form stacks and stumps.
Discord at coastline where the layers of rock are perpendicular to the coastline have different rates of erosion resulting in headlands and bays being formed. These headlands concentrate wave energy funnelling waves resulting in more complex erosion features and increasing rate of erosion of coves and bays.

Question 40

Assess whether sustainable management schemes are always the most appropriate for managing the risks at coastlines

Answer 40

Sustainable management surgeries can be appropriate to wye to reduce exploitation of the environment in HICs such as less construction at beach resorts but can be inappropriate in remote rural coastal locations that might depends on tourism for survival such as in LICs and seasonal jobs

Sustainable management strategies might include the use of hard and soft engineering however thier appropriate use requires specialist stakeholders who understand the principles of ICZM and littoral drift and sediment cells. However intermediate technology might be more appropriate for communities in LICs such as mangrove plantation and education and management systems to maintain shrimp farming and resources such as rubber and rope which locals depend on.

Question 41

Explain the ways of classifying coasts

Answer 41

Coasts can be classified using longer term criteria such as geology and eustatic changes in sea revel or shorter term changes such as inputs from rivers and waves.

Geology is the characteristics of the the environment which includes the lithology and structural arrangement of rock types. This can be used to classify coats as rocky, sandy or estuarine. They can also be classified as concordant where the layers of rock strata are parallel to the coastline such as the Dalmatian region of Croatia or discordant coastlines where the alternating rock strata is at an angle to the coastline

Another ray of classifying coats is through sea level change which is an eustatic change caused by steric changes. Emergent coastlines occur when tectonic processes lift up secotions of land forming raised beaches and relict/ fossil cliffs such as in the Isle of Arran. Submeegent coastlines occur when climate change causes sea level to rise as ice sheets and glaciers melt increasing the global sea volume flooding low lying land forming drowned river valleys such as rias

Shorter term criteria for classifying coasts includes sediment inputs where coasts recieve sediment inputs from waves and wind which vary with the wind as well as currents, wave movement and tectonic processes. Where erosion is greater than deposition there is a loss of sediment and the coastline retreats signifying an eroding coastline and where erosion is less than deposition there is a net gain of sediment and the coastline advances signifying an outbuilding coastline.

Question 42

Explain how geographical structure influences the coastal landscape

Answer 42

Geological structure is the 3D arrangement of rocks where strata is the different layers of rock and how they are arranged relative to one another, deformation which is the degree to which the the rock has been deformed by tectonic activity and faulting which is the prescience of major fractures and cracks in the rock due to rock movement

One the one hand geographical structure influences coastal type such as concordant coastlines which are created when rock starts runs parallel to the coastline such as at Lulworth Cove where the hard Portland limestone forms the back of the cove where the softer sands and clays have been eroded away as they are unconsolidated with more bedding planes so experience a faster rate of erosion. The harder rock acts as barrier to the soft rock behind it preventing erosion but fractures in the rock can be exploited and hollowed out to form caves arches stacks and stumps as arches collapse due to gravity.
Alternatively discordant coastlines where the different rock strata intersect the coast at an angle so the landforms vary. Less resistant rock are eroded at a faster rate to form bays whereas more resistant rock such as limestone remains in place, this differential erosion creates headlands and bays.

Geological structure also creates cliff profiles which are influenced by the resistance erosion of the rock and the dip of rock strata in relation to the coastline. Dip means the the angle of rock strata in relation to the horizontal with sedimentary rock formed in horizontal layers but can be tilted by plate tectonic activity. Horizontal dip produces a vertical profile with notches reflecting strata that are jointed or more easily eroded. A low angle of seaward dip produces a steep profile creating areas of overhanging rock which are vulnerable to rock falls due to undercutting. A landward dipping strata produces a steep cliff profile as downslope gravitational force pulls loosened blocks into place making a very stable profile with few rock falls. Faults also influence geographical structure as they represent major weaknesses in the rock layers around which rocks are more easily eroded. Fissures are smaller cracks which can be exploited by erosional processes such as hydraulic action along with faults can influence structure leading to wave cut notches and platforms. Folds are also bends in the rock which are produced by sedimentary rock layers being squeezed together by tectonic forces forming anticlines and synclines which are heavily fissured and jointed leading they are more easily eroded. It also increases erosion rates by increasing the angle of sea ward dip and by causing joint formation as the rock is stretched and compressed within synclines and anticlines.

Question 43

How can the permeability of rocks influence the stability of cliffs?

Answer 43

Cliffs which have impermeable rock overlying permeable rocks limit percolation and therefore are more stable as the rock will become saturated which prevents mass movement .
However cliffs which have permeable rock overlying non permeable rocks will leads to heavy rain being absorbed by and percolating through the unconsolidated material reducing friction between grains and lubricating lines of weakness such as bedding planes. This makes the cliff face heavier as it becomes saturated and leading to rotational slumping as the material will slide down the rain lubricated slip plane leaving the material behind.

Question 44

Why are some coastlines more threatened by rising sea level and coastal flooding than others?

Answer 44

One major reason is due the low lying nature of the coastline such as Kirbati which is composed of 33 coral atolls where the maximum height was so less than 3m above seas level and where many of the islands are very low lying and rising sea levels have caused fresh water sources and coconut trees to disappear as salt water polluted groundwater supplies. This will put increased stress on the inhabitants as livelihoods and sustenance is lost forcing them to move away.

This is also seen in Bangladesh where the unconsolidated delta sediment only lies around 1-3m above sea level . The delta is at the confluence of three river including the Ganges all of which converge in Bangladesh and empty into the Bay of Bengal. Storm surges Combe with out flowing river discharge from the Ganges river mixing both river and coastal flooding. The Triangular shape of the Bay of Be gal also concentrates storm surges as they move north resulting in more destructive waves.
Removal of vegetation also increases risk of coastal flooding from erosion and extreme weather events as every 100m of mangrove is wave heights are decreased by up to 40% but despite this 71% of Bangladesh’s mangrove forests have been retreated by up to 200m a year due to conversion into shrimp farms and deforestation for timber. Vegetation stabilises existing sediment and traps new sediment raising the height of the land above sea level and 1km belt of mangrove reduced storm surge height by 0.5m protecting the inhabitants and infrastructure further inland which will be left exposed.

Subsidence as low lying natural coastlines in estuaries and deltas are subject to natural subsidence through the settling and compaction of recently deposited sediment. Human activity also causes local subsidence and isostatic fall such as the drainage of saturated sediment in East Anglia to growing water abstraction to supply cities such as in Venice which reduces sediment volume and causes subsidence. Another reason is the weight of cities and built environments can also compress sediment as in seen in Venice leading to subsidence. Human activity in Bangladesh building 4000km of flood embankments prevents the deposition of fraud sediment and increases the effects of river flooding increasing subsidence as flooded land increases the weight.

Question 45

Explain the different aims of hard and soft engineering coastal defences

Answer 45

Hard engineering involves man made structures which are often every effective at preventing erosion in the desired area but are high cost and have significant environmental impact due to the use of non local materials and structures. One example is the Deltawerken in the Netherlands which I edited flood risk but reduced the length of defended coastline from 800km to 80km due to the building of dams and sluice gates. The Eastern Schelft Fam is as built with sluice gates that can open and close which allows salt marshes behind the dam to be maintained for wildlife and the storm surge gates allow for trade to occur. Zuider Zee saw a 30km barrier from creating a freshwater lake which land has been reclaimed for residential and agricultural use.

Also seen in Mappleton which was protected at a cost of £2million despite being valued at £650k to secure the B1242 road which connects the town to multiple others and trade. The scheme resulted in groynes and rip rap being constructed to counteract wave erosion in storm and spring tide conditions by reducing wave energy and building up the beach by reducing LSD and regrading of the boulder clay cliffs to prevent landslides and maintain road access.

Soft engineering strategies aim to work with and complement the physical environment by using natural methods of coastal defence. Methods such as beach nourishment where sediment is taken for offshore sources to build up the existing beach and dune stabilisation by planting pioneer plants such as marram grease which trap sediment and create sheltered areas from the wind reducing loss of sediment.

Question 46

Integrated coastal zone management in the Holderness Coast

Answer 46

HORNSEA
A CBA determined that a hold the line strategy should be out in place with new defences being built in 1994 including the repair and replacement of 19 groynes, flood walls and building rip rap at a cost of £5.2 million. This was tailored specifically to avoid damage to the beach front or deter holiday makers which is a major part of the local economy. Was regarded as successful as it reduced erosion to the south and allowed for new housing to be built close to the coast which was being eroded at a rate of more 1-2m a year.

Also seen in Mappleton which was protected at a cost of £2million despite being valued at £650k to secure the B1242 road which connects the town to multiple others and trade. The scheme resulted in groynes and rip rap being constructed to counteract wave erosion in storm and spring tide conditions by reducing wave energy and building up the beach by reducing LSD and regrading of the boulder clay cliffs to prevent landslides and maintain road access. However there’s a risk of outflanking as erosion may get behind where defences stop leading to rapid erosion inland and defences being undermined as well as the regraded cliffs showing signs of slumping and undercutting This has also led to South Cowdon seeing alarming rates of erosion south of Mappleton.

Another area was Spurn Head where a DO NOTHING strategy was put in place as no practical solution was available and sea defences were abandoned. This may lead to increased erosion of the spit and people homes and livelihoods being threatened. Differnet stakeholders such as environmental groups were not satisfied as 4 different ecosystems and and an important bird habitat behind the spit are left threatened as long as heritage and recreational sites which may be lost.

Question 47

HAITI VS JAPAN EARTHQUAKE RESPONSE

Answer 47

Haiti
Poorest country in the Western Hemisphere with 70% living on less than £2 a day
86% of people in Port au Prince live in slum conditions with poorly built infrastructure due to poor building codes
Loss of 25% of government officials so NGOs uncoordinated—> further deaths due to lack of relief and medical supplies as only part of airport operational and ports damaged
UN peacekeepers brought about Cholera epidemic causing more deaths to already starving and weakened people
Epicentre close to capital so seismic waves did not lose energy
Lack of public awareness and education on what to do in the event of an earthquake
Already recovering from tropical storm in 2004 and four hurricanes in 2008

220,00 deaths with 300,00 injured
30,000 commercial buildings collapsed due to lack of aseismic construction
By July 2010 98% of rubble remained uncleared with 1.6 million living in relief camps
World Bank wiped half of Haitis debt and giving extension the on payback of relief
Most if the relief came from neighbouring countries such as Dominican Republic which provided emergency water and medical supplies.

Question 48

CAUSES OF A SPECIFIC EARTHQUAKE

Answer 48

Haiti lies on a strike fault between east loving Caribbean plate and west moving North American plate so there was slippage along a conservation plate boundary that run through Haiti.
Epicentre was 25km west of Capital Port au Prince so seismic primary and secondary waves did not lose energy and reached in a short period of time.

Question 49

HAITI VS JAPAN EARTHQUAKE RESPONSE

Answer 49

Economic cost of $235bn largest in world history with magnitude 9 on Richter scale
Only 16,900 deaths with 130,000 displaced
330,000 buildings destroyed with 11 hospitals completely destroyed due to corrupt building officials
Tsunami wall’s rendered useless at Miyako due to land subsidence so waves washed over them with buildings creating funnelling effect allowing water to reach further inland

800 earthquakes of magnitude 4.5 or more were recorded following the main earthquake—> more collapse
Over 10 senior citizens died due to pneumonia in two weeks due to freezing and damp environment in flooded hotel

It took 11 months for the county to establish a Reconstruction agency to focus on local communities
50,000 personnel dispatched from self defence forces within two days and national police/ safety agencies mobilised
Annual earthquake drills on the 1st of September so people were educated
Automatic warning systems were triggered on technology allowing people to get to shelter
70,000 temporary homes built to house 300,000 people displaced
Major highway in Tohoku opened after 2 wells and the bullet train was fully operational within a month

Japan has an extremely good capacity to cope in earthquakes due to the strong governance of the county and wealth and development and investment into earthquake monitory and prevention methods

Question 50

What is a Hazrd Profile?

Answer 50

A description of the physical characteristics of a specific hazrd and determination of its various descriptors including magnitude, duration, frequency, probability and extent

Answer 51

230,000 deaths
Reached south India and srilanka 
$10bn
60% of srilanka fishing fleet destroyed
75% of GDP due to loss of tourism in Maldives