Flashcards in The Restless Earth Deck (82):
Describe the structure of the earth.
Crust 6-10 Km
Mantel. Thick layer of jam consistency. Ranges from 5,000C-1,300C
Outer core. Liquid made of iron.
Inner core. Solid iron can reach 5,500C. Normally 3,700C
Why so plates move?
The mantel is semi-molten. This means that certain areas get heated up, move to the side and fall.
Explain a divergent plate boundary.
Also called a constructive boundary.
Two plates move apart and magma goes up between the two. This can cool and form new land. This is how Iceland formed when the North American plate and the Eurasia plate moved apart. This also formed the mid Atlantic ridge.
What are the differences between continental and oceanic plates?
Continental plates are thicker and lighter.Oceanic plates are thinner and more dense.
What are the places where plates meet called?
Boundaries or plate margins.
What are the three types of plate margins?
Destructive, constructive or divergent and conservative.
Explain a destructive plate margin.
It happens when two plates are moving towards each other like along the coast of Japan.
When the denser oceanic plate meets the continental plate, the denser plate is sub ducted into the mantel and is melted. This can create volcanoes and ocean trenches.
What happens when two continental plates move towards each other?
They smash together but none of it is destroyed. Fold mountains can form here.
Explain a conservative plate margin.
It is when two plates are moving sideways past each other or moving in the same direction but at different speeds. This can cause earthquakes when one of the plates, suddenly jerks forward. This happens along the west coast of the USA.
How do fold mountains form?
They form when two plates move together. When the plates aren't moving, sedimentary rock will form in the depression between the two. This rock will form when a river carries sediment and deposits it into the depression. This will form sedimentary rock after millions of years. The depression where the rock forms is called a geosyncline.
When the plates move together the rock will get forced upwards and this will happen in a series of folds called anticlines and synclines.
What are anticlines?
Folds up in a fold mountain.
What are synclines?
Down falls in a fold mountain.
At what type of plate boundary do fold mountains form?
Destructive plate boundaries like in the west coast of North America.
What are the characteristics of fold mountains?
They are very high, with very rocky and steep slopes. There's often snow and glaciers in the highest areas and lakes in the valleys between the mountains
How do humans use fold mountains for farming?
Higher mountain slopes can't be used for crops so they are used for animals like goats and cows. Lower slopes are used to grow crops but the steeper ones can be terraced to make growing crops easier.
How do humans use fold mountains for hydro-electric power?
Steep sided mountains and high lakes make fold mountains good for hydroelectric power.
How do humans use fold mountains for mining?
Fold mountains are a major source for metal ores. Steep slopes make access to the mines difficult so zig-zag roads have been caved on the sides.
How do humans use fold mountains for forestry?
They are good for growing certain types of trees. They're grown on the steep valley slops and the wood is used for fuel, paper and building materials.
How do humans use fold mountains for tourism?
They have nice views which attract tourists. In winter, people do sports like skiing, snowboarding and ice climbing.
In summer, walkers enjoy the scenery. Tunnels have been drilled through some of the mountains to improve access.
Where are the alps? how did they form and how many people live there?
Central Europe. It stretches across Austria, France, Germany, Italy, Liechtenstein, Slovenia and Switzerland.
They formed 30 million years ago by a collision between the African and European plates. 12 million people live there.
How are the alps used for farming?
The steep upland areas are used to farm goats, which provides milk, cheese and meat.
Sunnier slopes have been terraced to plant vineyards like in Lavaux Switzerland.
In winter the animals are returned to the valley where they are kept in sheds. The farming type is dairy farming using a system called transhumance. (Seasonal movement of the animals)
Cable cars and pipes have been used to move milk around.
How are the alps used for hydro-electric power?
Narrow valleys are dammed to generate power like in the Berne area. 60% of electrify in Switzerland comes form hydroelectric power.
The power is used locally to power homes and businesses. Power is also exported to over towns, cities and other nations.
How are the alps used for tourism?
100 million tourists visit the alps every year.
70% of the tourists visit the steep, snow covered mountains in winter for skiing and snow boarding. In the summer tourists visit for walking, mountain biking and climbing.
New villages have been built to cater for the tourists like Tignes.
How are the alps used for mining?
Salt, iron ore, gold, silver and copper were mined in the alps, but the mining has declined dramatically due to cheaper foreign sources.
How are the alps used for forestry?
Scots pines are planted all over the alps because it's more resilient against goats. Trees are logged and sold to make furniture.
How have people adapted to conditions in the alps?
The soil is poor so animals are grazed in high areas.
Steep relief. Goats are farmed on the steep sides as they are adapted to it. Trees have been planted to protect against avalanches and rock slides.
How do volcanoes form at destructive plate boundaries?
At destructive plate boundaries when the oceanic plate goes under. It will melt in the mantle, forming a pool of magma. This will rise through cracks in the crust called vents. The magma erupts onto the surface.
Other than destructive plate boundaries where do volcanoes form?
At constructive margins where magma rises up in the gap between tow plates or where the mantel is very hot (hotspots) like in Hawaii.
What are the three types of volcanoes?
Composite, shield and dome.
Explain composite volcanoes.
Made of ash and cooled, erupted lava. This means many layers. The lava is usually thick and flows slowly when it gets out. This hardens quickly to form steep sided volcanos. This type emits ash as well e.g. Mount Fuji
Explain shield volcanoes.
Made of only lave. The leaves runny. It flows quickly and spreads over a wide area, forming a low flat volcano e.g. Mauna Loa
Explain dome volcanoes.
Made of lave only. The leaves thick. It flows slowly and hardens quickly, forming a steep-sided volcano e.g. Mount Pelée
How can scientists predict volcanic eruptions?
They can monitor tiny earthquakes, escaping gas, changes in the shape of the volcano. These mean an eruption is likely.
When did the Soufriére hills volcano errupt?
June 25th 1997. There were small eruptions in July 1995
How many were killed by the Soufriére hills volcano erruption?
What caused the Soufriére hills volcano erruption?
Montserrat is above a destructive plate boundary, where the Atlantic plate boundary is being forced under the Caribbean plate.
Magma rose up through weak points under the hills forming an underground pool of magma.
The rock above the pool collapsed, opening a vent , causing the eruption.
What were the primary impacts of the Soufriére hills volcano eruption?
Large areas were covered with volcanic material. The capital city of Plymouth was buried under 12M of mud and ash.
Over 20 villages and two thirds of homes on the island were destroyed in pyro clastic flows which was poisons and went at 150 MPH
Schools, hospitals, the airport and the port were destroyed.
Vegetation, farmland and forests were destroyed.
19 were killed and 7 were injured.
What were the secondary impacts of the Soufriére hills volcano eruption?
Fires destroyed many buildings, including local government offices, the police head quarters and the towns central petrol station.
The economy was distrusted as tourist stayed away and businesses where destroyed. The GDP fell.
The population declined. 8000 of the 12000 people left since the first eruptions in 1995. Most of them were young.
Volcanic ash improved soil fertility.
Tourism on the island is now increasing as people come to see the volcano.
What were the immediate responses of the Soufriére hills volcano erruption?
People were evacuated form the south to safe areas in the north.
Shelters were built to house evacuees. Some people had to live in them for 18 months which was very hot, no widows or privacy.
Temporary infrastructure was also built, e.g. Roads and electrical supplies.
The UK provided £17 million of emergency aid.
Local emergency services provided support units to search for and rescue survivors.
What were the long term responses of the Soufriére hills volcano eruption?
A risk map was drawn up and an exclusion zone created. The south of the island is still off limits.
The UK has provided £41 million to develop the north of the island. New docks, an airport and houses have been built in the north.
The Montserrat volcano observatory has been set up to try and predict future eruptions.
£10.5 million was spent to relocate people.
In 1997 £2400 was offered to adults how wanted to leave. People rioted as they wanted £20,000.
How do super volcanos form at hotspots?
Magma rises up through cracks in the crust to form a large magma basin below the surface. The pressure of the magma causes a circular bulge on the surface several kilometres wide.
The bulge eventually cracks, creating vents for lava to escape through. The lava erupts out of the vents causing earthquakes and sending up gigantic plumes of ash and rock.
As the magma basin empties, the bulge is no longer supported so it collapses spewing up more lava.
When the eruptions finished, there's a big crater (a caldera) left where the bulge collapsed. These can fill with water and form lakes.
What are the characteristics of super volcanos?
Flat. Not like volcanos which are like mountains.
Cover a large area. Much bigger than normal volcanoes.
Have a caldera. Unlike a normal volcano where there's just a crater at the top.
What are the effects of a super volcano eruption?
It will throw thousands of cubic kilometres of rock, ash and lava.
A thick cloud of super-heated gas and ash will flow at high speed from the volcano, destroying everything it touches. Everything within tens of miles will be destroyed.
Ash will shoot kilometres into the air and block out almost all daylight. This can trigger mini ice ages.
The ash will settle over hundreds of square kilometres, burying fields and buildings.
How do earthquakes occur at destructive margins?
Tension builds up when one plate gets stuck as it's moving down past the other into the mantle.
How do earthquakes occur at constructive margins?
Tension builds along cracks within the plates as they move away from each other.
What is the focus?
The point where the shock waves spread out from.
What is the epicentre?
The point on the Earth's surface.
Explain the Richter scale.
This measures the amount of energy released by an earthquake, called the magnitude.
The magnitude is measured with a seismometer.
It has no upper limit and is logarithmic meaning each level is ten times as powerful as the one before.
A major earthquake is one above 5
Explain the mercalli scale.
This measures the effects of an earthquake.
Effects are measured by an eyewitness using observations that take the form of words or photos.
It goes from 1-12
Explain the earth quake in a MEDC.
6th April 2009
6.3 on Richter scale.
Caused by movement along a crack in the plate at a destructive margin. The population was 70,000
Explain the preparation at the earth quake in L'Aquila.
There are laws on construction standards but older buildings don't follow them.
Italy has a civil protection department that trains volunteers to help with things like rescue operations.
Explain the primary effects at the earth quake in L'Aquila.
290 dead, mostly from collapsed buildings.
Thousands of buildings were damaged and destroyed meaning 70,000 were homeless.
A bridge and a water pipe were broken. The pipe in Paganica caused a landslide. Wildlife habitats were destroyed.
Cost of rebuilding was $1 billion. Thousands of young people moved away to find jobs. The government helped pay rent and gas and electrical bills were suspended.
Explain the secondary effects at the earth quake in L'Aquila.
After shocks hampered rescue efforts.
Fires in some buildings caused more damage.
The broken water pipe at Paganica caused a landslide.
Explain the immediate responses at the earth quake in L'Aquila.
Camps were set up for the homeless with water food and medical care.
Ambulances, fire engines and the army were sent in to rescue survivors.
Cranes and diggers were used to remove rubble.
International teams with rescue dogs were sent in to look for survivors.
Money was provided by the government to pay rent, gas and electricity bills were suspended.
A camp for 40,000 was built.
Explain the long term responses at the earth quake in L'Aquila.
The Italian PM promised to build a new town in the centre of L'Aquila.
An investigation is going on to look at why some of the modern buildings didn't survive the earthquake.
What is the LEDC earthquake case study?
Kashmir a region in north Pakistan
Date. 8th October, 2005
Size. 7.6 on the Richter scale.
Caused by the Indian plate being forced under the Eurasian plate.
Explain the preparation at the earth quake in Kashmir?
No local disaster planning was put in place.
Buildings were not designed to be earthquake resistant.
Commutation was poor, there are few roads and they are badly constructed.
Explain the primary effects at the earth quake in Kashmir?
80 000 dead. Mostly because of collapsed buildings.
128,500 injured 53,000 seriously so.
Entire villages and thousands of buildings destroyed.
3 million people homeless.
Water pipelines and electrical lines broken
80% of Uri destroyed.
6400 schools and 800 hospitals destroyed.
Lack of skilled workers cost $5 billion cost of $3.5 billion.
Broken sewage system. Two landslides affected 0.1KM squared. A landslide in Jhelum created a dam that blocked two rivers. There was a lack of clean water.
Explain the secondary effects at the earth quake in Kashmir.
Landslides buried buildings and people. They also blocked road access and cut of water and electrical supplies and telephone lines.
Diarrhoea and other diseases spread due to little clean water.
Freezing winter conditions shortly after causes more casualties and recovery operations were made difficult.
Explain the immediate responses at the earth quake in Kashmir.
Help didn't reach many areas for days or weeks. People were rescued by hand without equipment or help from emergency services.
Tents, blankets and medical supplies were distributed within months but not to all affected areas.
International aid and equipment such as hospitals and rescue dogs were brought in, as well as teams of people from other countries.
Explain the long term responses at the earth quake in Kashmir?
Around 40 000 people have been relocated from the destroyed town of Balakot.
Government money has been given to those homes that have been destroyed.
Training has been given to people to help rebuild more buildings as earthquake resistant.
New health centres have been built in the area.
80 nations donated a total of $6.8 billion.
The government set up the federal relief commission and the earthquake reconstruction and rehabilitation authority were set up to coordinate actives with NGOs.
What is the ring of fire?
The boarder between the pacific plate and the other plates. Lots of volcanos and earth quakes here.
What forms the Andes along the west coast of South America?
They are fold mountains. The Nazca plate is forced down by the South American plate.
What is the subduction zone?
Where a crust that has been put down is melted by the mantel.
Give an example of a passive or conservative plate margin?
At the San Andreas fault in California. The North American plate and the pacific plate are sliding past each other. They go in the same direction but the North American plate is moving faster.
What will be the effects of yellow stone erupting?
It would trigger other volcanos.
Everything within 100 miles would be destroyed.
80,000 feet ash cloud. This could block put the sun.
Mountains 1200 feet high would 3000 feet.
2.5 trillion tonnes of ash and rock in the air.
Global temperatures will fall 3-4C.
What were the features of the Japanese Tsunami?
11 march 2:46 PM 2011
9 on the Richter scale. Lasted six minutes. The tsunami happened 10 minutes after.
What causes the Japanese tsunami?
The pacific plate was sub-ducted under the North American plate, but no-one is sure.
What were the social impacts of the Japanese Tsunami ?
20,00 dead. People in a 20 km radius were displaced and won't be able to return to Fukushima. The risk of cancer is increased.
Transport and housing damaged. Many fires occurred including one at an oil refinery.
What were the economic impacts of the Japanese Tsunami ?
300 billion dollars of damage. Ports were damaged meaning a lack of trade as was Fishing. Japan is reliant on nuclear power and the industry has been affected.
What were the environmental impacts of the Japanese Tsunami ?
Farmland and agriculture damaged by floods. Radiation from a nuclear reactor was leaked and this causes plant mutation. Wild fire caused by a refinery fire.
What were the long term responses of the Japanese Tsunami ?
Music album "song for Japan" was produced.
Buildings were re-built.
The UN pledged to so anything to help.
What were the short term responses to the Japanese Tsunami?
The earthquake early warning system sent out a warning to millions. 200,000 shelters were setup. Portable water, food and blankets given out. Bank of Japan offered $183 billion to normalise the economy three days later. 20,000 US soldiers, 19 navel ships and 120 aircraft were sent.
Search and rescue teams from 45 nations came.
Air ports and roads closed meaning it was harder to produce aid.
The UK and Australia provided shelter boxes that could surpport 10
What was the preparation Japan had towards the tsunami?
It spends billions on Earth quakes and Tsunami protection. This is more than any other nation. Alarm sirens went off but people didn't listen to them as they thought the sea wall would protect them. They were 3 Meters high but weren't high enough.
Where are plate boundaries located?
On or close to plate boundaries. Around the pacific plate.
How does an ocean trench form?
At a destructive plate boundary, the heavy oceanic plate is sub-ducted and will melt under the lighter continental plate. In the ocean, sub-suction zones create deep trenches.
A long series of Peru-Chile trenches off the west coast of South America came about in this way.
They can also form when two oceanic plates meat and one is sub-ducted but these are rarer.
How did the Mariana Trench form?
The pacific plate sub ducts under the Philippine plate.
What can form next to ocean trenches?
Landforms can form. Some molten material can rise through volcanos located near the trench. They build up mountain ranges or chains of volcanic islands that lie parallel to the trench.
How can volcanos be predicted?
Measure the temperature.
Measure the amount of ash.
SO2 is released.
Ground deformations. Lave swells up under the ground causing the ground swell. Electronic tilt meters measure this.
How does Japan prepare for earthquakes?
On the 1st of September, they have earthquake drills.
Reinforced concrete and steel are slightly elastic so are used a lot in building.
They are strict building regulations meaning that all buildings are quake proof.
They are built to keep the weight off the floor.
People have special hats that protect them from falling materials and they go under tables.
Mass dampers act as pendulums.
Where is yellow stone national park?
In the north West of the USA in the state of Wyoming.