Term
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Definition
| Very thin layer of solid rockDensity between 2.7-3.2g/cm3Divided into continental and oceanic rock |
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Term
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Definition
| The boundary between the crust and mantle. |
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Term
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Definition
| Dark coloured solid rocks rich in magnesium and silicondesity between 3.4-5.5g/cm3Parts of the mantle are moving slowly in a semi plastic way due to the convection currents produced by radioactive decay. |
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Term
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Definition
| Made of nickel and iron, and is responsible for the earth's magnetismLiquid stateDensity between 10-12g/cm3 |
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Term
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Definition
| Made of nickel and iron in solid state due to immense pressureDensity between 12-18g/cm3Divided into continental and oceanic rock |
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Term
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Definition
| A sudden ground motion or vibration of the Earth. |
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Term
| How do earthquakes occur? |
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Definition
| Forces inside the earth become strong enough to fracture large massas of rock and make them move. This sudden break releases energy in the form of seismic waves, which travel through the earth. |
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Term
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Definition
| The exact point where an earthquake originates. |
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Definition
| The nearest point above the focus on the earths crust. |
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Term
| How are seismic waves recorded. |
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Definition
| With the use of a seismograph. It relies on the principle of one part of the instrument shaking, while the other part remains still. |
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Term
| Discuss the richter scale. |
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Definition
Measures energy released, but each unit on the scale means an energy increase of 10 times.
e.g 6 is 10 times more powerful than 5, and a 100 times more powerful than 4. |
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Term
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Definition
| PUSH (transverse) waves travel within the earthPASS through both solids and liquids.PRIMARILY recorded because they travel the fastest. |
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Term
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Definition
| SHAKE (longitudinal) waves travel through the earth but are STOPPED by liquidsSLOWER than P waves so are SECOND to arrive. |
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Term
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Definition
| Long waves travel only in the crustLarge movements so produce the most damageLast to be recorded because they travel the slowest. |
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Term
| What happens to shock waves when they meet a boundary? |
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Definition
| ReflectionRefractionChange velocity |
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Term
| How do we know the thickness and densities of the earth's zones? |
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Definition
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Term
| Describe continental crust. |
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Definition
| Forms the earths continents, and continues a little beyond their edges as continental shelves and continental slopes under the sea.Thickness varies.As the composition is on average like that of granite,continental crust is often called granitic crust. |
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Term
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Definition
| It's a thin,6km thick layer of crust beneath the sea floorsAs the composition is on average like that of basalt, oceanic crust is often called basaltic crust.Relatively young and heavy. |
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Term
| What is the thickness of the moho? |
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Definition
| Varies as the thickness of the crust varies. |
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Term
| Describe where volcanoes and earthquakes occur. |
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Definition
| In belts across the globe which can cross paths, e.g at the Indian Ocean.On land they tend to occur along high mountain chains.Under sea, belts are either found along the centres of oceans, e.g mid- Atlantic, or they pass through chains of volcanic islands.e.g Carribean.Trenches often run parallel to high mountains. e.g Peru- Chili Trench runs parallel to the Andes. |
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Term
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Definition
| The crust and uppermost part of the mantle. |
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Term
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Definition
Maintaining the balance in the earth's crust.
Different hights of continental areas (therefore different weights of rock), are supported and balanced from below. |
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