Tectonic Plates Flashcards
Oceanic crust
Thinner and more dense
Continental crust
Thicker and less dense
Destructive plate margin
Moving towards each other
Oceanic plate meets continental plate and the denser oceanic plate is forced down into the mantle
Creates volcanoes and ocean trenches
Creates fold mountain of the two plates crush together
Constructive plate margin
Two plates moving away from each other
Magma Rosie’s from the mantle to fill the gaps and cools creating new crust
Conservative plate margins
Two plates are moving sideways past each other
Or in the same direction at different speeds
Creates friction
Fold mountains
When two plates collide and the sedimentary rocks between the are folded upwards ->mountains Continental + oceanic Eg Andes Continental + continental Eg Himalayas Rocky and steep slopes Often snow and glaciers
Fold mountain case study - Andes
Farming
Farming : steep slopes are bad for growing crops so they are used to graze animals
Or terraced to make growing crops easier
Built- in terraces hold water
Maize, soya, cotton
Subsistence farming for personal consumption
Andes
Hydroelectric power
Steep sided mountains and high lakes make fold mountains ideal for generating hydro electric power
Easy to be dammed
Yucan project dam
Andes
Mining
Major source of metal ores
Steep slopes makes access to mines difficult so zigzag roads have been made in some places
Andes
Alpacas/ llamas
Alpacas produce fine cloth Llamas are used to carry goods Carry materials for irrigation and building into inaccessible areas Carry up to 25% of their body weight Females used for meat and milk
Yanacocha gold mine
Advantages
Population has grown from 30,000 to almost 240,000 in 2005
Brings jobs
Economy
Disadvantages
Lack of services
Increased crime rate from growing population
Rock is sprayed with poison that damages lakes and crops
The Andes basic facts
Runs through Peru, chile, equado, Columbia,Argentina
South America
Destructive plate margin
Nickel tin silver and gold are mined
Volcanoes
Formed
Formed at destructive plate margins where the oceanic plate goes under the continental plate because it is more dense
Melted and destroyed
Pool of magma forms
Magma tidied through cracks in crust called vents
Magma erupts into the surface forming a volcano
Composite volcanoes
Made up of layers of ash and lava Lava is thick and flows slowly Steep sides Vent up the middle Eg mount Fuji in Japan
Shield volcanoes
Made up of only lava Lava is runny Flows quickly and spread over a wide area Low and flat Eg mauna loa in the Hawaiian islands
Dome volcanoes
Only lava
Thick lava
Steep sided
Eg mount pelee in the Caribbean
Montserrat case study
Facts
June 25th 1997
19 killed
4-5 million m3 of rocks and gas
Montserrat
Causes
Above a destructive plate margin Atlantic plate being forced under the Caribbean plate Magma rose up through weak points Underground pool of magma Pool collapsed causing eruption
Monserrat
Primary impacts
Large areas covered with volcanic material
The city of Plymouth was buried under 12 m of mud and ash
Over 20 villages and 2/3 of homes k the island were destroyed by pyroclastic flows
Schools, hospitals the airport and port were destroyed
Vegetation and farmland destroyed
19 people died 7 injured
Montserrat
Secondary impacts
Fired destroyed many buildings incl. local gov. Office, police headquarters and petrol station
Economy and business destroyed by lack of tourism
Population decline 8000/12000 inhabitants have left
Volcanic ash improved soil fertility
Montserrat
Immediate responses
People evacuated for the south to safe areas in the north
Shelters were built to house evacuees
Temporary infrastructure eg road and electricity
UK provided £17 million of emergency aid
Support from local emergency services
Long term responses
A risk map
Exclusion zone
UK provided £42 million aid to develop both of the island
Montserrat volcano observatory set up
Super volcanoes
Much bigger
Can develop everywhere
Eg Yellowstone
Formation of a super volcano
1) magma rises up through cracks in the crust to form large magma basin below the earths surface- pressure forms a bulge
2) bulge eventually cracks creating cents for lava to escape through. Lava erupts causing earthquakes and plumes of ash and rock
3) bulge collapses
4) leaves over a Caldera
Characteristics of a super volcano
Flat
Cover a large surface area
Have a caldera
Consequences of a super volcano eruption
Thousands of cubic kilometers f rock ash and lava
Pyroclastic flows would burn and desires everything within 10 miles
Mink ice age- ash blocking out sun and heat
Ash would settle and bury fields
Earthquakes
Causes
Tension builds up from plates grinding against each other or getting stuck
Jerk past each other sending onto shockwaves
Shockwaves spread out for the focus and become weaker further away
The epicenter is right above the focus
Measuring
earthquakes
The Richter scale 1-9+
Magnitude of the earthquake
On a seismometer
Major earthquake are 5+
