Thursday, 10 November 2011

Earthquakes and why they happen


Section
Detail
Key Ideas
  1. Earthquake strength is measured on the Richter Scale and the intensity of their effects on the Mercalli Scale.
  2. Earthquakes happen because of the stress where tectonic plates meet.
Terms
Distribution, Richter Scale, seismograph, Mercalli Scale, focus, shock waves, epicentre.
Starter
Main
   1. TDIT
   2. Using H p18 answer the following questions:


  •    What are earthquakes?
  •    How dangerous are they?
  •    How many earthquakes are there each year?
  •    Where do they occur (what is their distribution or global pattern)?
  •    What is the link with where volcanoes occur?
   3. What is the difference between a seismometer and a seismograph?
   4. What do the Richter and Mercalli scales measure?
   5. Explain how an earthquake measuring 6 on the Richter scale is 100 times stronger than one measuring 4.
   6. What number on the Mercalli scale is an earthquake likely to be if it is the top story on the BBC news? Does this depend on the country the earthquake occurs in?
   7. On what type of plate boundary do most earthquakes happen? Explain why many strong earthquakes occur along destructive plate margins.
   8. Why are tectonic stresses lower along constructive plate boundaries?
   9. Draw a diagram to illustrate the terms; focus, shock waves, and epicentre.
   10. Read eyewitness accounts of earthquake survivers
Plenary
    Run through 'Earth shakes, rattles and rolls' powerpoint. 

BBC Earthquakes Video - Starter