Flashcards
Tectonics and the Earths structure
Cards in this deck (19)
- 1There are 2 types of crust name and describe eachContinental- Makes up the land, thicker (25-90km), less dense and can float on top of oceanic crust
Oceanic Crust- Found under the sea, Thinner(5-10km), More dense, younger and often destroyed beneath continental crust - 2Describe tectonic platesThe earths crust is separated into lots of different sections- these are called tectonic plates, which float on top of the mantle. These sections of crust move because of the molten rock underneath them is moving.
- 3What was Wegeners theory on continental driftMillions of years ago, all the continents were joined together to make a super continent (pangaea) and over time they have drifted apart
- 4Describe Convection CurrentsHeat from the core causes the mantle to warm and the hot mantle rises. The colder fluid falls due to gravity and this creates convection currents within the mantle
- 5What is a hotspot and how is it formedA hotspot is a volcanic area that forms as a tectonic plate moves over a point heated from deep within the Earths mantle
1) The tectonic plate moves over a stationary plume of magma
2) The magma erupts and creates volcanoes
3) This leaves behind island chains such as Hawaii ( formed over millions of years by volcanic eruptions thousands of miles from the edges of the pacific plate) - 6What happens at a destructive/convergent boundaryContinental and oceanic crust move together
Oceanic crust is denser so subducts and then melts back to magma (destroyed)
- explosive volcanoes
-Violent earthquakes
- 7what happens at a Constructive/Divergent plate boundary- 2 oceanic plates move apart
-lave erupts
-New crust is formed on sea bed
-underwater volcanoes (e.g. mid atlantic ridge)
-Gentle Earthquakes
- 8What happens at a Conservative plate boundary- Tectonic plates move in different directions or at different speeds
-Plates are locked together by friction
-Pressure builds up until a plate breaks along a fault line
-No volcanoes
-Violent Earthquakes
- 9What is an earthquake?Convection currents in the mantle cause the tectonic plates to move. sometimes plates don't move swiftly past each other and cause pressure to build up in the plate boundaries. when the pressure releases, energy is released in the form of an earthquake
- 10How do we measure earthquakesRichter scale- Measures the magnitude of an earthquake using a seismograph- which is based on the size of the seismic waves emitted
Mercalli Scale- measure the intensity and damage caused by an earthquake. These scales are important to business and property owners in earthquake affected areas - 11Why do people live in areas of earthquakes and volcanoes-Tourism e.g. blue lagoon- creates jobs for people
-Fertile Soils
-Family connections
-Religious reasons
-Benefits outweigh the potential dangers
-People may live in earthquake proof houses and therefore feel safe
-Geothermal energy- can heat water
Minerals (diamonds) - 12What sort of Planning have they provided for earthquake or volcanic areas-secure heavy appliances to studs on walls- less likely to move
-latches on cupboards- so doors don't swing open
-safety film over windows- so glass doesn't break as easily - 13What to do in an earthquake scenarioturn off electricity and keep away from power cables
-turn off gas
- listen to the radio
Supplies: Food, Water, Medical supplies, general supplies- batteries, portable radio
also an example is japan carry out an earthquake drill, so everyone knows what to do in this situation - 14Preparing for an eruptioncreate an exclusion zone
evacuate residents
emergency supplies of food etc
funds to be able to deal with the emergency and good communication system needs to be in place - 15Forecasting/Predicting an earthquakelaser beams can be used to detect plate movement
A seismometer is used to pick up the vibrations in the earths crust
Radar gas escapes from cracks in the earths crust. levels of random gas can be monitored- a sudden increase may suggest an earthquake - 16Forecasting/Prediction of VolcanoesTemperatures around the volcano rise as activity increases
The higher the sulphur content of these gases released, the closer the volcano is to erupting
thermal imaging techniques and satellite cameras can be used to detect heat around volcano
chemical sensors used to measure sulphur levels - 17How do they decide where to build a building in an earthquake prone areaThey have developed maps to show weak areas that are particularly unsafe- land use planners develop zoning restrictions that will prevent the construction of unsafe building structures in earthquake prone areas
- 18How to build earthquake proof buildings-bolting buildings to their foundations
-providing support walls called shear walls- these are made with reinforced concrete ( concrete with steels bars embedded in them)- which helps strengthen the structure and help resist rocking forces.
- cross bracing- walls reinforced with diagonal steel beams
base isolators- act as shock absorbers- alternate layers of steel and an elastic material- absorb sideways motion - 19How to build earthquake proof skyscrapers- anchored deeply into the ground
-reinforced framework with stringer joints than an ordinary building has
-framework makes the skyscraper strong enough and yet flexible enough to withstand an earthquake.
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- Flashcards on Tectonics and the Earths structure, created by Emily Fynn on 30/05/2015.
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- Emily Fynn
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