Japan Case Study Notes

Japan

Q1 Tectonics

The meeting of four tectonic plates à

Destructive plates create Fold Mountains to form the series of islands.

Mt Kirishima = explosive composite volcano. 10% of the most active volcanoes are in Japan.

Japan is a part of the Pacific ring of fire which follows the Western boundary of the Pacific plate and here occur around 90% of all earthquakes.

Pacific plate sub ducts beneath the North American and Philippine plate to create the Japan Trench. ß Most volcanoes found along this point.

On average, the Pacific Plate is moving west at about 9cms per year, and the movement has produced major earthquakes in the past — nine earthquakes of magnitude 7 or greater since 1973.

http://www.ouramazingplanet.com/1048-japan-tectonics-explosive-geology-ring-of-fire-110314.html

Q2 Landscape

Japan is approximately 375,000km², consists of 2,456 islands in total.

Japan is located in Eastern Asia. It’s a series of islands east of the Korean peninsula.

The Japanese islands are the summits of mountain ridges uplifted near the outer edge of the continental shelf therefore 73% of Japan is mountainous (high relief) with a mountain range running through each of the main islands. (e.g. the Japanese Alps) The highest point on the island is Mount Fuji at around 12,400ft. ß High risk of landslides

There are a few plains and river basins many of which are near the coast and heavily populated. Areas around Tokyo for example are reclaimed (popular for buildings and harbours around the city). None of the populated plains or mountain basins are extensive in area. The largest, the Kanto Plain, where Tokyo is situated, covers only 13,000 square kilometres.

With expanding population there have been challenges with land space leading to human modifications:

·         Land extensions (reclaimed land, marshes)

·         Artificial islands e.g. Port Island in Kobe

·         Reclaimed land from river deltas, drainage

·         Carved/degraded mountainsides

Rivers no longer than 400kms, often small and steep river Shinano is the longest.

Islands difficult to get inland, rivers fast flowing and violent, roads rare therefore rural populations hard to reach in emergencies.

Q3 People

 Violent earthquakes, volcanic eruptions etc. high death toll but well prepared due to MEDC status and funds. See individual events for specific examples à

Q4 Management

Scientists carry out seismic monitoring of plates to provide warnings with sirens, education drills and emergency packs etc. ß However, the warning for the recent tsunami in 2011 was sent out only 15minutes ahead of the tsunami.

After 1995 in Kobe, the Japanese government created new laws to increase the standard of building regulations to withstand earthquakes.

Tectonic events

Kobe 1995  

An earthquake measuring 7.2 on the Richter scale in January 1995 of which the epicentre found beneath Kobe City ß significant damage was incurred because the epicentre was shallow in the crust hence the quake reached the surface quicker with less energy lost.

ß Caused by a slip fault between the pacific plate sub ducting beneath the Philippine plate.

Effects:

·         Pancaked houses (flattened) leaving 300,000 people homeless.

·         Crashing of gas pipes and electricity. ß +150 Fires in the city leading to over 1,000 deaths.

·         Hanshin Highway collapsed. ß Early morning low impact but cut of transport routes. Double storey highways, collapse also damaged surrounding buildings.

·         Liquefaction weakened building structures cracked roads.

·         5,500 killed in total.

Emergency resources were sent out but many did not reach those who needed it because of transportation problems.

‘Robo-rat’ was developed after the quake to find people in the rubble safely.

Photos of Eastchurch Gap

 

These are some of my favourite snaps that I have taken of one of my favourite places: BEACH! (more specifically Eastchurch Gap) anyway I thought I would share them with you just to make my blog look a bit more friendly than constant essay after essay. Besides its geography revision anyway for the physical part of the Unit 2 exam retake. Coastal processes! Also did some case study revision work today. Woo. Hope you like them and case studies will be up soon :) x

Second practice report Question 3

‘Tectonic activity poses varying degrees of challenge for the communities experiencing it. Discuss.’

Introduction

There are many different ways in which tectonic landforms are useful to people. Around volcanoes for example there are often rich fertile soils as a result of eruptions in the distant past; this physical factor attracts human population. There are also human factors that cause people to live in areas of tectonic hazard as cities with good infrastructure, employment and support attract people and poverty, isolation and commitment can also hold them there. To answer this question we must consider the definition of ‘community.’ There are many secondary effects of tectonic hazards on different populations but I will comment in reference to the immediate population of the area which the hazard affects, such as states, regions or countries depending upon the scale of the hazard. Different groups will be compared, defined by different human situations. I will also consider a range of tectonic activities in Montserrat, Japan, Sichuan and the Cascade mountains, comparing the difference between types of earthquakes and volcanoes whilst linking the effects of such hazards between LEDCs and MEDCs.

Montserrat

 Montserrat is a LEDC British island in the Caribbean, heavily dependent upon tourism and agriculture. The island is 11miles by 7miles and hosts the destructive volcano: the Soufriere Hills Volcano on the plate boundary where the North American Plate is sub ducted beneath the Caribbean plate. In July 1995 the first in a continuous series of volcanic eruptions began on the island that has continued indefinitely with the last ash eruption occurring in 2006. This posed a difficult challenge to the people of Montserrat as the south side of the island was covered by pyroclastic flows of hot, explosive lava eruptions that have rendered the land uninhabitable for another 5 years. This has destroyed farm land, homes and the tourist industry leaving high unemployment, poverty and inflation. The perception of risk was low as education was limited and the volcano had been dormant throughout recorded history. 

Though the death rate of the initial volcanic eruption was relatively low at 23 people (warnings from steam and magma dome triggered evacuation) there are now problems for the remaining population on Montserrat as a population of 12,000 has been reduced down to 6,000 after mass relocation. Relocation is not considered an easy option for the community though as local says “The threats of moving are far greater than staying here.” After the eruption locals were offered opportunities to relocate to Australia, America or the UK. This is not a viable option for many though as locals are not educated with sufficient skills to achieve employment in these countries and many remain behind because they do not perceive how large the risk is.

Therefore many challenges exist in every day survival. As secondary hazards the volcano also emits sulphurous gases and ashes which are poisonous and have led to high rates of asthma and illness (especially in children and the elderly). As a result of volcanic material falling into the sea small tsunamis of a maximum height of 5m have caused damages to the fishing industry and the few remaining coral reefs on which it is dependent. Ash falls, lahars and falling shards of exploding rock have also damaged vehicle operation and visibility causing crashes and the degradation of the environment. Financially people were unable to produce income as without subsistence farming they were reliant on imports from one ferry boat over long distances, therefore causing the price of food to increase dramatically and employment to be limited to the island. As a result of poverty, unemployment and temporary housing in shelters, the crime levels rose with social tensions, later causing riots against the British government. This information was compiled from the video by the Panamerican organisation of health.

Overall there is a high degree of challenge for the communities facing volcanic activities in Montserrat as when considered in the risk hazard equation above: The hazard is highly volatile, the people are made vulnerable by their isolation and development status, and they have a low ability to cope. It is only because of the attachment with the British government and aid from other MEDCs that the risk has remained as contained as it now is. Without external help with evacuation projects and compensation the death toll would be higher and the challenges more dangerous.

Mt St Helens

Mt St Helen is a composite volcano in the cascade mountain range of the USA. Unlike the Soufriere Hills, volcano Mt St Helens is on mainland America in a MEDC. Because of this the challenges for the community in the Cascades are of a very different scale to those in Montserrat. Both volcanoes were formed on a destructive plate boundary as here the cascades sit above the point where the small Juan De Fuca plate sub ducts beneath the North American plate.

The volcano erupted in 1980 after weeks of uncertainty. Technically the eruption at St Helens was more destructive as 57 people were killed, over double that in Montserrat’s blast. However most deaths were caused by secondary hazards in Montserrat and at St Helens 1km3 of volcanic material was erupted covering a much larger area of land. There was a low risk of disaster in the cascades however as the population was so low. Being on high terrain development was difficult and the area was also protected as an area of beauty for a tourist destination. Most land use was for agriculture.

Furthermore as a MEDC, there was also monitoring of the volcano by scientists who had extensive historic records of the volcano’s tectonic activity. They had technology to measure the likelihood of eruption through seismic readings from the volcano and were supported by government evacuation efforts. Warning also came from visible evidence as before the eruption there were ashes emitted from the central vent that reached around 16miles in height and the pressure caused the summit to bulge outwards for many weeks after an earthquake that measured 4.2 on the Richter scale shook the area. This aided evacuation attempts.

However it could also be argued that the warnings did not help as the volcano created interest and was covered heavily by the media. This attracted tourists to the area to see the volcanic activities. Furthermore several secondary features of before the official eruptions were also damaging with Lahars that wiped out housing and avalanches as the result of earthquakes that wiped out the entire northern face of the mountain (estimated to be the largest debris avalanche in history). After the eruption 200 houses had been destroyed, along with roads and rail links making the area entirely inaccessible. Furthermore lakes and glaciers were destroyed by the eruption in turn destroying popular tourist attractions. The spirit lake was a famous example of this.

Key issues now are that the area has been unpopular the eruption in 1980 and human inhabitants are unlikely due to the risks attached. Mt St Helens has continued erupting very frequently with eruptions and earthquakes in 1986 and 2005 and other smaller occasions. Environmentally many plants and animals have returned. The key challenges for the local communities are balancing the risks of volcanic activity against the benefits. Farmers live near to the volcano but development is not possible because of the risk and therefore the population and wealth of the community is restricted. Information found from sources:  ‘Mount St Helens: Mountain Transformed.’ National Geography website and Wikipedia.

Sichuan

In May 2008 Sichuan province in China suffered an earthquake that measured 7.9 on the Richter scale, the largest earthquake China has experienced in 50years which killed over 240,000 people. This is a much larger death toll than above mentioned volcanoes and even though each hazard has equal potential to cause disaster more people are killed as a result of earthquakes than volcanoes.

Sichuan is on a destructive plate margin between the Indian and Eurasian plate and the earthquake occurred along a mid-fault. As a result of the plate boundary type there are also Fold Mountains with high relief in the area. The hazard here however had a much higher potential to become a disaster than the two previous examples as the area was densely populated with 15million people living in the area. Sichuan is a river basin in a valley and as a secondary impact of the earthquakes extensive landslides have hit the basin and blocked the river. This creates a long term problem for the community as fishing industries cannot access the river as it is welling up into a lake behind the debris. Furthermore 30 reservoirs were also burst causing the area to flood and water sources were therefore limited and contaminated.

Furthermore the people of Sichuan were vulnerable with a low ability to cope. Despite China’s rapid development the GDP per capita is only 21% of the national average and as a result there are no building regulations in this poorer area. When the quake hit the main victims were schools, an astounding 9,145 were destroyed leaving on of the largest populations of victims as children at an estimated 5,000. This has created challenges for the community of Sichuan as it is under the rule of the one child policy and the surviving parents are devastated. Being a poorer rural area dependent on farming, people in these areas are often dependant on their children for income and their future security when ill and unable to work. Many parents have accepted compensations of just under £6,000 for the poor building structure of schools but there are still many in uproar. Recent protests have led to political tensions in the communist country as parents and children as young as 8years old have been arrested for protests.  Information found from the Telegraph.

Conclusion

In conclusion there are a great many ways in which communities are challenged by tectonic activity beyond the initial death toll. Secondary hazards are important when considering challenges as landslides and floods can not only kill but also cause long term sanitation problems. Many hazards cause continuous, frequent damages which could be argued to have a higher impact than singular hazards. Population and location is also important when considering evacuation, mobility and the potential for tectonic activity to create disaster.

Practice report for question two, Unit 4 Tectonics

Explain why Tectonic processes produce a variety of contrasting landscapes. 70mrks

Introduction

Tectonic processes are the varying types of events that are caused by movement of magma in the mantle and outer core. As a result of heat from the inner core, many eras ago the Earth’s crust split into plates driven in different directions by the resulting convection currents.  All landscapes and landforms are affected by past or present tectonic processes somehow. Many of these examples began on plate boundaries, in magma chambers within the ground or are rare results of tectonic hotspots. The size, shape and material of the resulting landscapes vary greatly depending on the type of tectonic process and the scale of the event. In this essay I will be examining the differences between these processes and their resulting landscapes, comparing the above details of each.

Seismic Activity

Earthquakes commonly occur on conservative plate boundaries but epicentres can also be found in areas of great pressure such as subduction zones on destructive boundaries or in the central vent of an explosive volcano. Seismic activity rarely has a very high impact on the landscape though as not being igneous activity it does not create dramatic new landforms. However in extreme cases, they do have the potential to change landscapes entirely. In Sichuan, China, May 2008 an Earthquake measured 7.8 on the Richter scale, so powerful that it was felt in Bangkok around 2000km from the epicentre. Immediately the landscape was only changed by collapsed buildings, however when the earthquake hit Beichuan city the secondary impacts were landslides that dammed river valleys in the basin causing extensive flooding and fast rising lakes in place of the river. Man-made dams and reservoirs were also affected, 30 dams were damaged and several reservoirs burst altogether causing low lands to flood. As a result of the earthquake new lakes have been formed, valleys filled and mountainsides destroyed, hence changing the shape of the landscape.

This earthquake was caused by the friction between the Indian plate and the Eurasian plate on a destructive boundary. The epicentre was caused by a slip in the mid margin, known as the Yingxiu-Beichuan fracture. As a result of the pressure Fold Mountains have been formed and are vulnerable to subsequent landslides. This information has been adapted from the Times 13^th May, 2008 and geology.com.

Intrusive Landforms

As shown in Sichuan, tectonic processes don’t necessarily have to involve lava to create new landscapes. Intrusive landforms can also change the shape of the landscape to varying levels of extent.  Dartmoor is the largest outcrop of granite in Britain with and area of 275mi and is proposed to be part of the exposed Cornubian batholith which is also cause to many other outcrops, some of which are found in Bodmin nearby or the isles of Scilly. Dartmoor is 17km thick in places but only a few hundred metres are exposed above ground to make wide flat moor lands and dense, impermeable granite tors.

The batholith was formed in the early Permian period by the pressure of a magma plume beneath the crust. As the pressure was so powerful the magma pushed into gaps in the crust to create a magma chamber. From here the magma could not find a way to the surface and eventually after the crust had moved away from the plume the magma began to cool. As the magma cooled underground the process was slow so granite rocks with large crystals were able to form, making a batholith. As the country rock above the batholith had changed over time water seeped through to the batholith and weathered the granite causing it to crack, eventually the country rock eroded away enough to expose the tors and make a new landscapes, some areas of the batholith were either eroded or are still covered meaning several different landforms appear separate but are actually part of the same batholith.

However not all intrusive landforms have any effect on the landscape at all. From recordings of underground granite, less than 20% of the Cornubian batholith’s surface is estimated to be exposed. In order to prevent a magma chamber from becoming a volcano the above country rock must be strong enough to withstand the pressure of the magma over 1000c in temperature. Batholiths can only ever create new landscapes with severe erosion over millions of years. Many batholiths remain underground without exposure. This information was found on Wikipedia and Geocases2.co.uk.

There are other types of intrusive landforms many of which don’t have the potential to create whole landscapes. An example includes the volcanic plug on which sits Edinburgh Castle. This is only around 50m higher than the land now and only large enough to accommodate the castle, creating a round hard granite mound that sits near the city centre. The plug used to be the central vent of a volcano that when made extinct cooled inside the volcano. As time passed the outer volcano eroded and sediment was deposited evenly to leave a thin column of granite. This has a rather different effect from the hundreds of square miles of granite in Dartmoor but shows the potential for volcanoes to create new landforms even when they are extinct. Information found from Geocases2.co.uk.

There are also sills and dykes which act as extensions of batholiths. When magma chambers are formed the magma pushes through the country rock in an attempt to reach the surface. Dykes push vertically through faults and folds and sills push through bedding planes horizontally. These cool in a similar way to the batholith to form rocks with large crystals that mix with the surrounding country rocks to sometimes form different rock types. Also like the batholiths these rocks are exposed when the above country rocks are eroded. An example of this is the Whin Sill in northern England on which Hadrian’s Wall was built. This sill appears on the landscape like a thin long series of hills covering the thin band of Dolerite in a wall structure beneath. The hills are significantly high but no wider than 60ms and stretch over 20km. As the sill is the result of more than one batholith the Whin Sill creates multiple paths and features including one of Britain’s most famous waterfalls, the High Force.  Though smaller than batholiths sills and dykes have the potential to create varied landforms within the landscape.

Volcanic Landscapes

However when considering Dartmoor and the Whin Sill in comparison to all tectonic made landscapes, they are very small. The Indian Deccan traps are also large land masses of igneous rock only instead of the 275 square miles of Dartmoor; the Deccan traps cover 200,000 square miles, engulfing western central India. The traps are also as much as 2kms thick, so large they are theorised to have changed the climate of the entire planet. The traps are made from flat lying flood basalts and have created giant soft sloped mountains with edges with a step like appearance as the lava cooled in layers.

 The Deccan traps were created by a constructive tectonic plate boundary between 60-65million years ago. As the plates tore apart the crust faulted leading to multiple fissure eruptions from the mantle. As the faults were large and created without intense pressure the lava erupted in the form of flood basalts. The lava was pure, hot and non-viscous, allowing it to disperse over the large spaces of North West India until the fissures were blocked by the volcanic rocks.

As the lava cooled quickly outside of the mantle it formed small grained basalts that have been eroded easier than coarse grained granites formed intrusively. The Deccan traps were predicted to cover an area almost four times as large before erosion which suggests that even though they may create a larger landform than Dartmoor now, the impact on the landscape may be less over time as the resistant granites of the Cornubian batholith are likely to last over a longer time than the flood basalts of the Deccan Traps. This information was found on the website for the Oregon State of Education: volcanoes.

However there are varying types of volcanic activity to be considered. Hawaii is a series of volcanic islands in the Northern Pacific ocean stretching in an arc shape over 5,800kms long of at least 129 volcanoes. Mauna Loa is an example of these volcanic islands and covers around 90km2. This makes Mauna Loa the largest current shield volcano in the world and it rises as far as 17kms above sea level. This information was found on volcanolive.com.

The landscapes of Hawaii were created by the pressure of a magma plume and weaker oceanic crust. The magma plume was proposed by Wilson to be a fixed point of intense heat energy in the mantle. As heat rises extreme pressure is pushing up through the crust until it breaks through to erupt in pure basaltic lava floods, similar to those that formed the Deccan traps. However these eruptions form a volcano as they occur through a central vent. As the magma is non-viscous and pure it builds on the sea floor to form a wide smooth sloped shield shaped volcano with wide flat landscapes. As volcanoes move away from the hotspot they also decline into new landscapes as they erode. These are atolls, submerged islands that often host coral reefs. Eventually each island declines into a sea mount (some in Hawaii as old as 47million years) meaning that like the Deccan traps, each landform has no lasting impact on the landscape. However the hotspot is still active meaning it continues to create new landforms unlike the declining Deccan traps. The information on the formation of hotspots was found on a Geo Fact sheet and Wikipedia.

Continental Rifting

Tectonics can further create new landscapes through the effects of continental rifting. A famous example of this is the African Great Rift Valley which stretches over 5,000kms long. The rift valley is a dramatic stretch in which steep sided hills drop into deep basins that are either filled by lakes, the Red Sea or remain as land. Mountains also line the basin with both shield and composite volcano types, examples include Mt Kilimanjaro and Mt Kenya (steep sided slopes).  

Eventually all basins will fill with the Red Sea as the Danakil depression is 100ms below sea level. The total area of the basin is over 92,000km2 and annual surface run off is less than 1km3. Combining the hot, dry African climate with an enclosed basin, with high levels of volcanic activity, the Danakil desert is the hottest place on Earth and irrigation potential is zero.

The Great Rift Valley was created when the African and Arabian plates parted on a divergent boundary 35million years ago. As the plates were torn apart a section of land in between the plates sank downwards to create a new basin, lava then joined the plates back together forming the new valley sides. As the basins are left on weak crust shield volcanoes are common here. In addition to this there is also a magma plume causing the hills to bulge and create mountains. These processes formed the contrasting hills and basins of the Great Rift Valley. This information was found in the article East Africa’s Great Rift Valley: A Complex Rift System and a blog on scientificamerican.com.

Conclusion

In conclusion there are many varying landscapes produced by different tectonic processes. As much as the landscapes created will be different between the tectonic influences of a batholith and a volcano different volcanoes in different locations will also produce contrasting landscapes. In the Great Rift Valley there are a variety of contrasting landscapes created by multiple tectonic processes; this is also possible as one area isn’t necessarily limited to one example of tectonic activity.