Restless Earth - Earthquakes 0.0 / 5 ? GeographyRestless EarthGCSEAQA Created by: 12BECreated on: 30-04-17 13:57 What is an earthquake? A sudden and brief period of intense ground shaking 1 of 32 What is the cause of earthquakes? A build up of pressure between plates due to friction 2 of 32 What plate margins are earthquakes associated with? All of them 3 of 32 Why do earthquakes occur at destructive plate boundaries? The oceanic plate can become stuck against the continental plate so it cannot subduct, building up pressure 4 of 32 Why do earthquakes occur at constructive plate margins? Tension builds up along cracks as the plates move away from each other 5 of 32 Why do earthquakes occur at collision plate boundaries? The force of the land moving upwards builds up tension if one or both of the plates get stuck 6 of 32 Why do earthquakes occur at conservative plate margins? Tension builds up when the plates are grinding past each other and get stuck 7 of 32 What happens when the tension gets too great? The plates are forced past each other in a sudden jerk, sending out shock waves 8 of 32 Where do some of the strongest earthquakes occur? Conservative plate boundaries such as the San Andreas fault 9 of 32 Where is there a lot of earthquake activity? The pacific ring of fire 10 of 32 Where do most of the least severe earthquakes happen? Constructive plate boundaries 11 of 32 Where do earthquakes begin? The focus 12 of 32 What is the focus? The point in the earth's crust where the earthquake starts 13 of 32 Which type of earthquake cause less damage? Deep-focus earthquakes 14 of 32 Which type of earthquake is felt the most? Shallow-focus earthquakes 15 of 32 Why do deep-focus earthquakes cause less damage? The shock waves have further to travel so dissipate on their way to the surface 16 of 32 What is the epicentre? The point directly above the focus on the surface where the waves are strongest and cause the most damage 17 of 32 What are shock waves? Vibrations in the earth caused by the sudden plate movement 18 of 32 What are the two directions of shock waves? Longitudinal and Transverse waves 19 of 32 Which waves move the land up and down? Longitudinal waves 20 of 32 Which waves move from side to side? Transverse waves that move from side to side 21 of 32 Which type of wave causes the most damage? Transverse waves 22 of 32 What are the two earthquake scales? The Richter scale and the Mercalli scale 23 of 32 What does the Mercalli scale measure? The effects of the earthquake 24 of 32 How is the Mercalli scale measured? Eye witness observations, words or photographs 25 of 32 What is the Mercalli scale? 1-12 in roman numerals 26 of 32 What does the Richter scale measure? The size or magnitude of an earthquake 27 of 32 How is the Richter scale measured? Seismographs (a shaking pen on a rotating drum) 28 of 32 What is the Richter scale? A logarithmic scale with no upper limit 29 of 32 What does a logarithmic scale mean? An earthquake with a magnitude of (x+1) is 10 times more powerful than an earthquake with a magnitude of (x) 30 of 32 Which scale can show only one result per earthquake? The Richter scale 31 of 32 Which scale can show more than one result per earthquake? The Mercalli scale (higher closer to the epicentre) 32 of 32
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