Tectonics Flashcards
What are the Earths core facts
Inner core is solid
Outer is liquid
Centre is very dense
Temp ranges from 4400-6000°C
What is the Mantle?
Mantle is made up of silicon based rocks
Part nearest the core is rigid
Layer above is called the asthenosphere which is semi molten
Temp is between 1000-3700°C
What are the charectersitcs of the Crust?
Made up on silicon-based rock
There is continental and oceanic
Continental crist is thicker and more dense
Oceanic crust is thinner and less dense
What are tectonics
Slabs of crust floating on mantle
How are plates moved by convection currents?
Lower parts of the asthenosphere heat up and become less dense and rise. As they rise the top cools and beckmes more dense (sinking). These convection currents create drag on the base of the tectonic plates causing them to move.
What are convection currents
Circular movements of semi-molten rock
What are plate boundries
Where plates meet creating movement
What are Convergent boundries?
Plates moving towards eachother. (Along south america)
What are Convergent plate boundries oceanic and continental?
When oceanic plates meet continenal, the less dense oceanic plate is forced donw destroying mantle creating volcanoes and ocean treanches.
What is Convergent plate bounbries continental?
When two continetal meet, plates collide and the ground is foulded upwards creating mountains
What are Divergent boundries?
Plates move away from eachother causing magma to rise from mantle to fill the gapcand cools, creating new crust. (Mid atlantic bridge)
What are Conservative boundries?
Where two plates are moving in the same direction but at different speeds. (Along the west coast of usa)
How do convergent plate boundries form volcanoes
the ocianic plate is forced down into the mantle where it is melted forming a pool of magma. The magma rises through the cracks of crust called vents. It erupts at the surface as lava forming a volcano
How do divergent plate boundries form volcanoes
Magma rises into the gap created when the plates move apart forming a volcano
How do Hot spot volcanoes form
They form in the middle of tectonics and occur where a plume of hot magma from mantle moves towards the surface causing a large flow of heat. The magma can break through the crust and reach the surface where there is an eruption and volcanoes form.
How do Composite volcanoes form
Occur at convergent plates. Subducted oceanic crust contains lots of water reacting with magma to create gases causing the subducted crust to erupt.
WhaT are the Composite volcanoes characteristics
Explosive eruptions Ashy explosions which deposits ash Andesitic lava High silica content (thick and sticky) Steep sided cone as laca can't flow far
What are the charectertics of Shield volcanoes
Occur at hotspots or divergent plate boundries
Not very explosive and only lava
Erupt basaltic lava
Low silica content (runny)
Flows quickly forming low, gentle sided volanoes
How do convergent plate boundries form earthquakes
Tension builds up from one plate getting stuck as they move down
How do divergent plate boundries form earthquakes
Tension builds up along cracks within the plates
How do conservative plate boundries form earthquakes
Tension builds up when plates grinding past eachother get stuck
What do moment magnitude scales measure
Energy released by n earthquake
What is the focus of an earthquake
The point where the earthquake starts
What is Shallow focus
Eathquakes caused by tectonic plates moving near the surface
0-70km
What is Deep-focus (less damaging)
Earthquakes formed by crust previously being subducted into mantle moving towards the centre of the earth, hearing up or decomposing.
(70-700km)
How do earthquakes cause Tsunamis
Earthsquakes that cause the seabed to move displaces lots of water spread from the epicentre.
What is the Epicentre
Point on the Earth’s surface that’s straight above the focus
How do you predict earthquakes
Lasers can detect movement of tectonics
Vibrations in cruts can be monitored by seismometers
Can measure gases that escape cracks in crust
Rocks will expand from increased pressure
How to predict volcanoes
Tiny earthquakes or changes in shapes of the volcano from activity in the magma chamber
Thermal imaging cameras seeing changes in temp
Analys gases escaping volcano (sulfurous)
Long term planing for tectonic hazards
Emergency services Building designs Educating people on what to do Plan evacuation routes Emergency supplies
Short term planning of tectonic hazards
Provide vitals and supplies
Treat injured
Recover dead bodies
Rescue people
Earthquake in japan (9.0 magnitude)facts
Triggered a tsunami (hundreds of thousands of building destroyed)
Tsunami cut of power to Fukushima power plant causing meltdown
Damage to roads and rails
Was unexpected to be so big
Thousands of building damaged
Sever liquefaction causing building to sink
Pakistan earthquake (7.6 magnitude) facts
Caused landslides and rockfalls
Unpredicted earthquake
80,000 deaths
Tens of thousands injured
Hundreds of buildings damaged (3 mill people homeless)
Water pipelines and electrial lines broke
Diarrhoea and other disease spread due to lack of clean water
Freezing winter conditions cause more casualties
What was Japan Sendia’s short-term relief
International aid
Search and rescue/soldiers
Transport amd communications were restored (in couple of weeks)
Power supply restored (in couple of weeks)
What is the Long-term planning in japan
Authorities gsve advance warning of earthquake and tsunami
Buildings became much more resistent
Automatic breaking on bullet train
What was Pakistanis short-term relief
Army was slow to respond
India refused to help from pollitical tension
Help didn’t come for weeks
Little equipment or help from emergency services
Supplies were limited and took long time to come
What is Pakistan Long term planning
Fault lines were still poorly monitored in Himalayas
Avsence of building laws meant weak structures
Poor quality material used
