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| Question | Answer |
| EARTH STRUCTURE: Crust | CRUST: (forms the lithosphere) -made up of the surface crust and upper (solid) mantle -100-200km thick -6378km from the core -divided into the continental crust (25 to 90km thick) and the oceanic crust (11-16km thick) |
| EARTH STRUCTURE: Mantle | MANTLE: -composed of silicon, oxygen, magnesium, iron, aluminium and calcium Made up of 2 parts: 1. semi-rigid lower mantle (mesosphere) (3000 degrees) 2.upper mantle (atmosphere) (800 degrees) -mass in atmosphere is at a semi-molten state -heat from core (moving in a conventional upwelling) re-melts and melts outer mantle (can break out forming a volcano) |
| EARTH SURFACE: Core | CORE: -radius of 3500km -consists of iron and nickel -made up of a molten outer core and a solid inner core -temperatures of 5000 to 7000 degrees |
| EARTH STRUCTURE DIAGRAM |
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| PLATE TECTONICS: Definition | DEFINITION OF PLATE TECTONICS: -a theory explaining the structure of the earth's crust and many associated phenomena as resulting from the interaction of rigid lithospheric plates which move slowly over the underlying mantle. -solid rock that forms the outer surface of the earth (lithosphere) in segments |
| PLATE TECTONICS: Introduction | INTRODUCTION: -massive, irregular, slabs of solid rock containing both continental and oceanic crust. -vary in size -move in different directions due to conventual upwelling of heat from the core -each plate moves a certain amount each year -this movement causes earthquakes to occur -believed that due to tectonic movement the continents that we have today were formed |
| PLATE TECTONICS: Movement | |
| PLATE TECTONICS: Margin movement | MARGIN MOVEMENT: -there are three types of plate margins which cause this movement: 1. convergent plate margins (plates collide or converge) 2. divergent plate margins (plates diverge or separate) 3. transform plate margins (plates transform or slide past each other) -if a plate slides under another its called a SUBDUCTING plate |
| PLATE TECTONICS: Margin movement diagram |
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| PLATE TECTONICS: Convergent | CONVERGENT: -plates move toward each other,which produces zones which compress and collide -this results in either surface crumpling or crustal subduction -where this occurs between an oceanic and continental plate, the oceanic will subduct this is due to the continental crust being much thicker and stronger than the other -this creates an oceanic trench on the oceanic plates subduction zone -on the continental plates collision zone, hill and mountains can form |
| PLATE TECTONICS: Divergent | DIVERGENT: -the dragging and pushing apart of plates produces a rift within which new crustal material forms as molten rock rises from the mantle -this separation can form, mountain ranges, ridges, or even rift valleys |
| PLATE TECTONICS: Transform | TRANSFORM: -occurs when when plates slide past each other, neither creating or destroying the crust (although can cause the crust to ripple) -often located in relatively shallow areas but cause violent earthquakes |
| EARTHQUAKES: What is it? | WHAT IS IT?: -earthquakes are the shaking and vibration of the earths crust that takes place as a result of plate movements -it is a geomorphic hazard (hazard of the earths surface) -some of these movements are stronger than others and this is measured on the richter scale -seismology is the branch of science concerned with earthquakes |
| EARTHQUAKES: Why do they occur? | WHY DO THEY OCCUR?: -when the stress created by the process of tension and compression is released, a fault is produced within the crust and a series of vibrations or seismic waves spread out from the break point -the focus- is the point within the earth where an earthquake rupture initiates (where the pressure is greatest is when the focus is closest to the surface) (the closer to the focal point the greater the effects) -the epicentre- the point on the earths surface above the focus where the vibrations are most intense -as the waves from the focus pass through rock they distort it and produce a rolling, wave-like like motion -if the shock waves pass through the ocean a tsunami may occur -an earthquake can be categorised into 3 sections: 1. foreshock- warning sign, indicates the start of a larger earthquake to come 2. mainshock- the largest earthquake in a series (causes most damage) 3. aftershock- smaller earthquakes after the mainshock (due to pressure of mainshock) |
| EARTHQUAKES: When and where? | WHEN AND WHERE?: -the ring of fire receives most earthquakes and volcanic activity and accounts for 80% of worlds earthquakes -most affected areas include; New Zealand, Papua New Guinea, Japan, Canada, USA and South America |
| EARTHQUAKES: Measured, Recorded and Predicted | MEASURED, RECORDED AND PREDICTED: 1. seismograph- measures ground motion (greater movement=more extremes) 2. seismogram- ground motion recorded by seismograph 3. frequency- number of cycles occurring in a unit of time 4. magnitude- the size of an earthquake based on motion (measured on a richter scale) 5. intensity- the measurements on the earthquakes effects (how bad it is) 6. the richter scale (next slide) |
| EARTHQUAKES: The richter scale | THE RICHTER SCALE: -divides the size of the earthquake into categories (magnitudes-estimates of energy released) -shown in whole numbers and fractions, ranging from less than 2 to 10 (this means its a logarithm scale) -the magnitude is increased 10 times for every one on the logarithmic scale |
| EARTHQUAKES: Richter scale diagram |
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