Unit 1C - The Restless Earth Flashcards

Question

Who originally proposed the theory of plate tectonics?

Answer 1

Alfred Wegener

Answer 2

Deep inside the thick mantle layer of the Earth, the extreme heat from the Earth's core causes mantle rock to melt. As the rock becomes liquid, it becomes less dense than the material above it and starts to rise towards the surface. The molten rock (magma) rises and attempts to break through cracks in the crust where possible. The magma in the mantle layer will then interact with the crust (often due to friction from the moving mantle rock) causing sections of the crust to move towards or away from each other. Any excess magma, now that it is far away from its source of heat, will start to cool and solidify, and as the rock becomes more dense, the rock will sink back deeper into the deeper into the mantle, where it will become heated again.

Answer 3

Continental plates | Oceanic plates

Answer 4

Continental plates are usually thick plates that form at land masses/continental areas.

Answer 5

Oceanic plates are usually thinner plates that form at the bottom of ocean floors.

Answer 6

* 35-100 km (thick) * Rocks can be very old * Generally contains 'light' rocks that are less dense * Example: Granite

Answer 7

* 6-10 km (thin) * Rocks can be very young * Generally contains 'heavy' rocks that are more dense * Example: Basalt

Answer 8

A constructive plate margin is a boundary where two plates are moving away from each other. They are moved as the convection currents push the plates further away. Landform: Mid-ocean ridge (a gap in the seabed) Example: Iceland

Answer 9

Under the oceans

Answer 10

A destructive plate margin is a boundary where two different types of plate are moving towards each other. They are moved due to the convection currents in the mantle. One denser and heavier oceanic crust plate moves towards the lighter but thicker continental crust plate and the oceanic crust plate is forced underneath. This creates a deep ocean trench where the two plates meet. The movement of this plate creates a subduction zone, where huge amounts of friction mean that earthquakes can be felt. As the oceanic plate continues to sink, the plate is heated by the surrounding mantle and begins to melt. The increased amount of molten material (or magma) creates more pressure on the magma chamber of any local dormant or active volcanoes. Magma starts to rise and makes its way to the surface quickly, causing violent volcanic eruptions and composite cone volcanoes to be formed . In some cases the mountain areas are pushed further up as the continental crust collides with the oceanic crust and fold mountains are created. Landform: Subduction zone, ocean trench and fold mountains Example: Nevado del Ruiz in Colombia (composite cone volcanoes) and the Andes Mountains (fold mountains)

Answer 11

A collision zone (plate margin) is a boundary where two continental crust plates are forced by convection currents in the mantle to move towards each other. The continental crust cannot be pushed down into the mantle, so that plates push each other upwards. Sometimes violent earthquakes can signal plate movement. A good example of where this process can be seen in action is where the Indian Plate is moving into the Eurasian Plate. The resulting battle between the two plates has created an uplift of the mountains in this area, creating the highest range in the world, the Himalayas. They start when rivers deposit sediment in a depression between toe large plates. As more and more sediment is laid down on the seabed, pressure is put on it and it forms sedimentary rock. The plates then move towards each other and the rock is crumpled upwards to form the folded mountains. Landform: Fold mountains Example: Himalayan Mountains

Answer 12

Sedimentary

Answer 13

Geosyncline

Answer 14

A conservative plate margin is a boundary where two plates are slipping past, rather than moving towards or away from each other. No new crust is being created and crust is not being destroyed. In some cases the plates might be moving in two different directions (one to north and one to south), or the plates could be moving in the same direction, but at different rates. The plates do not pass each other smoothly. There is a huge amount of friction between the two plates, which can build up over time. When the pressure of the friction is released to allow the plate to move, the plate will be 'jerked' forward and the momentum can cause an earthquake. One example of a place where this is happening is along the San Andreas Fault, which is a fault line that separates the North American Plate and the Pacific Plate. Both plates move northwards, however, the North American plate is moving at a faster speed. Landform: Fault lines Example: San Andreas Fault, California

Answer 15

Converging

Answer 16

Extrusive means that the feature is formed above the Earth's surface, when magma flows out onto the surface as lava and igneous rock remains.

Answer 17

Antrim plateau

Answer 18

The plateau was formed by a series of basalt lava flows that built up on top of each other, creating an extensive extrusive feature. 1. Before the activity that created the volcanic features, the bedrock was made up of old layers of sandstone, which had been covered with clay and limestone (chalk). 2. The first stages of volcanic activity were explosive and produced huge amounts of dust and fragmented rock. This became what is known as the lower basalt. Following this, further volcanic activity brought more lava flows, and the lava came through cracks and fissures in the ground (which can today be seen as dykes and sills). Many small ash cone volcanoes spewed huge amounts of lava. 3. Following a period of relative inactivity (which allowed some of the basalt to be weathered and broken down into red, iron-rich soils) new activity (called the Interbasaltic formation) caused localised eruptions, which created features such as the Giant's Causeway. 4. The final period of tectonic activity brought further lava flows to the surface through fissures that covered the land and formed the cap of the Antrim Plateau.

Answer 19

The Giant's Causeway

Answer 20

The Giant's Causeway is a great example of a spectacular extrusive feature which is caused when the cooling conditions for basalt are perfect. Geologists believe that columns occurred when lava erupted into an ancient river valley where the lava became trapped and ponder, and cooled very slowly. While the thick lava flows were cooling, some of the surface areas were flooded with water to form temporary lakes. Some of this floodwater could have been from heavy rainfall or from rivers. As the lava started to cool cracks started to appear on the surface, similar to what happens when mud dries in the sun. The lava lost heat upwards into the atmosphere and downwards into the ground, causing the column shapes to extend many metres. Therefore the hexagonal columns associated with the Giant's Causeway were a result of perfect cooling conditions. Tension caused by different rates of cooling and shrinking within the column split the column into regular tablets of stone, with curved joints that fitted together in a ball and socket arrangement. The hexagonal shape was the most efficient way to fill a space.

Answer 21

Dolerite is an igneous rock type, which is similar to basalt but is cooled a little more slowly. Dolerite is harder and more resistant to erosion than basalt.

Answer 22

1. Volcanic plugs are intrusive features. (Intrusive means that the feature occurs below the Earth's surface, when the magma does not reach the surface). They are formed when magma is forced up from under the crusts to move up inside the vent of a volcano. Magma pours through the vent of the Slemish volcano as lava and covers the surrounding area with lava, which hardens into basalt. 2. As volcanic activity ends the vent is blocked by a lump of hardened magma, which forms rock called dolerite. Dolerite is harder and more resistant to erosion than basalt. 3. Over time rain, ice and wind weathers away the softer basalt slopes of the volcano, leaving the harder dolerite exposed above the flat landscapes of the Antrim Plateau.

Answer 23

Slemish Mountain

Answer 24

Market Rasen in Lincolnshire, England | 27 February 2008 at 0056

Answer 25

5.2 on the Richter scale

Answer 26

The cause of this earthquake was nothing to do with the movement of major plate boundaries, as Market Rasen is nowhere near the edge of a plate boundary. However, Intraplate earthquakes can happen, and in this case the tectonic pressures from the North Atlantic ridge and the African plate caused stress which led to a sudden rupture along the strike slip fault line in the local area. Some geologists even think that the fault line that runs from Doncaster to Lincoln might be the reason for this movement.

Answer 27

* The estimated cost of damage to homes was around £10 million. * Some buildings were reported to shake for up to 30 seconds. * There were 15 small after shocks recorded (between 1 and 2 on the Richter scale) over the following weeks and months. * It was the biggest earthquake to hit the UK in 24 years. * There was some structural damage to local homes and businesses - roofs collapsed and chimney pots fell from a few houses. Firefighters attended three properties to make chimneys safe. * Birds and pets became very agitated and 77 hens died in Pete Sargent's shed, which was located directly above the tremor. * There were no deaths, but one man, 19 year old David Bates, suffered a fractured pelvis when a chimney smashed through the roof and landed on him as he lay in bed. A stone cross had fallen from St Thomas' Church, damaging the church roof and dislodging tiles before smashing onto the ground. * The spire at St Mary Magdalene Church at Waltham, Leicestershire was also damaged, costing around £100,000 to repair. * The earthquake was felt as far away as Bangor, Northern Ireland and Bournemouth. * Emergency services all over the North of England were called by people who had woken up to their house shaking (5,000 calls in one hour).

Answer 28

An earthquake is described as a fault rupture that generates seismic waves.

Answer 29

The place where the earthquake originally occurs.

Answer 30

The place on the Earth's surface which is the shortest distance from the focus.

Answer 31

Seismograph

Answer 32

We can identify that major earthquakes occur in zones of activity, which coincide with the plate boundaries that are spread across the surface of the Earth.

Answer 33

Liquefaction | Tsunami

Answer 34

Liquefaction occurs when an earthquake hits an area and shakes the wet soil. The shaking causes the water within the soil to start to rise to the surface, and this process turns solid soil and rock into a liquid mud. Buildings will start to sink and tip over as the support for the foundations is waterlogged and cannot maintain the weight of the buildings.

Answer 35

A tsunami is a large wave which is created when an underwater earthquake sends shockwaves through the water, causing a surge of water to move towards the coastline. Often the energy transferred due to a tsunami can travel for thousands of miles across the oceans. 1. A rupture in the sea floor pushes water upwards and starts the waves moving. 2. The waves move rapidly across the deep ocean, reaching speeds of up to 500 km/h. 3. As the waves near land, they slow to 45 km/h but get squeezed upwards by the sloping beach and the waves start to increase in height. 4. The waves climb to 10-40 metres in height and move inland, destroying everything in their way.

Answer 36

The Great Tohoku earthquake Japan, Friday 11 March 2011, 14:46 (Local time) Eurasian plate and Pacific plate

Answer 37

9.0 on the Richter scale

Answer 38

Japan lies in one of the most active tectonic regions in the world. Both the Philippine Plate and the Pacific Plate are moving towards the Eurasian/ North American Plate at a fairly fast rate. This is a destructive boundary, where a subduction zone has formed. A huge amount of friction built up over time, leading to a megathrust earthquake.

Answer 39

1. Death and injury 20,352 people died (approx. 20,000) 5,314 people were injured (approx. 5,000) 130,927 people were displaced (approx. 131,000) 2. Nuclear crisis 5m high tsunami barrier 9m tsunami wave came ashore Flooded the plants generators and electrical wiring People lost energy supply, took time to restore 3. Defences ineffective Japan had spent billions of dollars building anti-tsunami defences at heights of 12m Tsunami washed over them, ineffective Flood water moved 6 miles inland Destroyed houses, factories, roads and other buildings 4. Damage 332,395 buildings destroyed/damaged by earthquake/tsunami 2,126 roads '' 56 bridges '' 26 railways '' 300 hospitals damaged 11 hospitals destroyed Estimated 23,000 cars and trucks were destroyed/damaged Ports were closed for nearly 3 weeks One dam ruptured and another six were found to have cracks 5. Power supplies Around 4.4 million households in NE Japan were left without electricity Power blackouts were experienced for around 3 months in many areas

Answer 40

1. Foreshocks and aftershocks Earthquake was preceded by a number of foreshocks (one measuring 7.2 on March 9th) and hundreds of aftershocks 2. Tsunami Tsunami hit shoreline 30 mins after earthquake 40m high Devastated entire towns and lead to loss of life Pollution was carried by water inland Sources of clean drinking water were affected in some cases for up to a year 3. Land subsidence Coastal areas in Japan suffered land subsidence Beachfronts in some areas dropped by more than 50cm More susceptible to flooding

Answer 41

1. Economy Cost: Estimated $235 billion Estimated 5 years to rebuild 2. Tsunami Only 58% of people heeded warnings The water hit 49% of those who did not heed the warning 3. Further casualties Three members of the Japan ground self-defence force died whilst conducting relief operations An estimated 922 people died as a result of the harsh living conditions since the earthquake 4. Nuclear energy Earthquake led to meltdown of seven reactors Evacuation of local area and a 12 mile exclusion zone (affecting 200,000 people) Radiation levels at one point were over 8 times normal levels Radioactive water and leaks contaminated local areas 5. Transport Sections of Tohoku Expressway were damaged Sendai airport was hit by tsunami wave 4 trains derailed 1,100 sections of rail line needed to be repaired 6. Rebuilding Japan Move Forward Commitee Proposed that young adults and teenagers could help rebuild parts of Japan devastated by the earthquake

Answer 42

1. Landmass movement The quake moved parts of NE Japan 2.4m closer to North America, making parts of Japan wider than before 2. Coastline movement A 250 mile stretch of coastline dropped by 0.6 m, allowing the tsunami to travel further inland 3. Plate movement Estimates say that the Pacific Plate has slipped westwards by between 20-40m 4. Seabed movement Seabed near epicentre shifted by 24m Seabed of the coast of the Miyagi province moved by 3m 5. Earth axis shift Earthquake shifted the Earth's axis by between 10-25cm, shortening the day by 1.8 microseconds 6. Liquefaction Occurred in many parts of Tokyo on reclaimed land Around 30 homes were destroyed Around 1,046 buildings were damaged 7. Aftershocks 900 aftershocks since earthquake Some of which were over 7.0 on Richter scale Killed people Damage to electrical supplies Damage to Higashidori nuclear power plant 8. Antarctica Seismic waves from earthquake caused massive slabs of ice (one the size of Manhattan island) to fall from the Sulzberger Ice Shelf.

Answer 43

1. Earthquake prediction 2. National Disaster Prevention Day 3. Earthquake-proof buildings 4. Early warning systems

Answer 44

1. Earthquake prediction Japan has spent over £70 million trying to predict earthquakes 2. National Disaster Prevention Day Every year on 1st September (Anniversary of the Great Kanto earthquake, 1923) Earthquake and tsunami drills to make sure that emergency and rescue services are ready for any disaster 3. Earthquake-proof buildings Japan spends billions of pounds on buildings that are designed to be resistant to the effects of earthquakes Buildings built since 1981 use techniques to be more flexible and less affected by liquefaction, e.g. Shock absorbers, flexible steel frames and deep foundations 4. Early warning systems World's most sophisticated earthquake and tsunami early warning systems The tsunami warning system was set up in 1952 with 300 sensors The Earthquake Early Warning System in Tokyo fetches data from 100 seismographs across Japan

Answer 45

1. Refugees 2. Rebuilding 3. Evaluating the emergency response 4. Tsunami barriers 5. Social factors 6. Economic factors 7. Aid

Answer 46

1. Refugees Earthquake created over 300,000 refugees Resulted in shortages of food, water, shelter medicine and fuel for survivors Temporary shelters were built by the army 2. Rebuilding Japanese government set up 'Reconstruction Design Council' Government announced that more than 23 trillion Yen would be made available to aid rebuilding programmes over 10 years 3. Evaluating the emergency response Many Japanese schools were designated as evacuation centres There were not equipped Since earthquake, upgraded centres to save and sustain life in the next big emergency 4. Tsunami barriers New 18m high barriers around nuclear power stations 5. Social factors Many festivals went on as normal during the summer months in an effort to raise spirits 6. Economic factors After the earthquake, the Japanese government and many Japanese companies(Toyota, Honda) wanted to restart production in factories. However, they faced supply problems, as many of the factories that produced their components were severely damaged following the earthquake and tsunami. They also faced energy use restrictions whilst the Japanese government fixed the power supply. 7. Aid Aid organisations in Japan and worldwide responded to the event. Japanese Red Cross received $1 billion in donations (mainly from overseas) Japanese Red Cross distributed 30,000 emergency relief kits and 14,000 sleeping kits in the evacuation centres near Sendai

Answer 47

``` The Haiti earthquake Haiti, Tuesday 12 January 2010, 16:53 (Local time) Enriquillo-Plantain Garden fault North American plate Caribbean plate ```

Answer 48

7.0 on the Richter scale

Answer 49

The Earthquake in Haiti was caused by movement at the boundary of the Carribean and North American Plates. In this area the Carribean Plate is moving eastward in a strike-slip (conservative) motion. The movement is not smooth and takes the form of a number of jolts, which can produce earthquakes. In the area where this earthquake struck there had been little movement or activity for 250 years. This earthquake is reckoned to have caused a slip of about 1.8 m.

Answer 50

1. Location Earthquake took place very close to the capital city, Port-au-Prince, a very densely populated part of the country. 2. Death and injury An estimated 222,570 died An estimated 300,000 were injured 1.3 million were displaced ``` 3. Damage 97,294 houses were destroyed Hospitals collapsed Airport damaged Port damaged Roads were blocked with debris More than 1,300 schools were destroyed ``` ``` 4. Poverty Haiti was already exceptionally poor before the earthquake 145th out of 169 countries Poorest country in Western Hemisphere Earthquake worsened conditions further ```

Answer 51

1. Aftershocks 52 aftershocks (measuring 4.5 or more) over the next month Caused further damage 2. Mini-tsunami A 'mini-tsunami' was reported in the small fishing town of Petit Paradis Three people were swept out to sea and died 3. Damage Earthquake focus was shallow, which increased the intensity of the shaking Caused more damage to natural ecosystems, buildings and property 4. Location Port-au-Prince's residential areas were built on hillsides They tumbled down the slopes due to the force of the earthquake Deforestation had occurred in recent years When earthquake occurred, landslides happened

Answer 52

1. Industry and employment One in five jobs were lost Clothing industry in Haiti accounts for more than 2/3 of exports Clothing industry was severely hit by earthquake 2. Homelessness Many people continued to sleep in streets, on pavements or in cars They were afraid that structures would no be able to withstand aftershocks 3. Aid Impact of earthquake ---> Nearly a week for relief efforts to be organised properly Haitian government had to hand over control of airports/ports to US government to hasten and ease flight operations Medical supplies ran out (antibiotics) 4. Health risks Many dead bodies remained unburied Began to decay and decompose in heat and humidity Caused serious health concerns for survivors 5. Crime Prison Civile was destroyed, 4,000 inmates escaped Slow distribution of resources led to sporadic violence and looting in Port-au-Princ 6. Rebuilding International Haiti Reconstruction Commission, headed by Bill Clinton and Haitin Prime Minister Jean-Max Bellerive Over £3.42 billion was pledged internationally to rebuild Haiti

Answer 53

1. Physical Very few impacts on the physical environment 2. Relocation In April, Haitian Government began to relocate thousands of refugees north of the capital to a more secure location This was due to the threat of mudslides and flooding from the rainy season 3. Out migration In the months that followed, many people started to return to the rural areas where they lived and farmed prior to moving into the city before the earthquake

Answer 54

1. Earthquake prediction 2. Buildings 3. Emergency services

Answer 55

1. Earthquake prediction Haiti did not have an organised system for trying to predict or warn people about earthquakes or potential natural disasters. 2. Buildings Many of the buildings in Haiti were temporary constructions and not built to withstand the most basic damage. 3. Emergency services The emergency services were inadequate and unprepared for any form of rescue following the disaster. Many more people would have died if international aid organisations and governments had not stepped in when they did.

Answer 56

1. Refugees 2. Aid 3. Rebuilding 4. Evaluating the emergency response 5. Cholera 6. Food and Economic security

Answer 57

1. Refugees Over 3 million people were left homeless initially. Six months later, in July 2010, number of people in relief camps was 1.6 million. Almost no transitional housing had been built. 2. Aid International Red Cross US government organised, through USAID programme, aid. US response grew to 20,000 civilians and military personnel. US Vaccination programme, inoculated 1 million people. 3. Rebuilding By July 2010, six months later, 98% of the rubble remained. This hindered the aid response. 4. Evaluating the emergency response It took a while for emergency rescue teams to reach devastated areas. British search teams were the first to reach Leogane (near the epicentre of the earthquake) on 17 January 2010. The Red Cross described the town as 'severely damaged ... the people there urgently needed assistance'. 5. Cholera Late October 2010 ---> Outbreak of cholera. Required further relief efforts. Cholera treatment facilities were established. By the end of 2010, more than 3,300 had died of cholera. 6. Food and Economic security Aid agencies aimed to promote the agricultural sector. This would hopefully increase food productivity and increase farm incomes.