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# 4. measuring activity

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### Transcript

• 1. TECTONIC LANDSCAPES MEASURING MAGNITUDE
• 2. SPECIFICATION DETAIL• 3.1d The measurement of earthquake magnitude (the Mercalli and Richter scales).• Diagrams showing the characteristics of focus and epicentre.
• 3. LEARNING OBJETIVES• Know the differences between the Mercalli (intensity) and Richter (magnitude) scales.• Explain how earthquakes occur with reference to the epicentre and focus of earthquakes.
• 4. DEFINITIONS • Watch Seismograph: Here• Mercalli scale: (intensity)Uses seismic scale to measure the intensity of an earthquake. It isused to measure the effects of an earthquake.• Richter scale: (magnitude)A logarithmic scale used to express the total amount of energyreleased by an earthquake(It is a base 10 logrimithic scale: e.g. 5.0 on the Richter scale has ashaking amplitude 10 times larger than one that measures 4.0, )assign a single number to quantify the energy released during anearthquake.
• 5. HOW ARE EARTHQUAKES MEASURED?The Richter scale can beused to measure themagnitude (power) of atremor using aninstrument called aseismograph.It is a logarithmic scalewhich means that a size‘6’ earthquake on theRichter scale is 10 timeslarger than a size ‘5’ and100 times larger than asize ‘4’.
• 6. HOW DOES A SEISMOGRAPH WORK?
• 7. THE MERCALLI SCALEThe Mercalli scale rates an earthquakes magnitudebased on observations of the damage it causes on ascale of 1 to 12. Items shake from Buildings collapse: shelves: scale 5 scale 10
• 8. Richter ScaleIntensity Magnitude Observations (Mercalli)(Mercalli) (approx. comparison)I No effect 1 to 2II Noticed only by sensitive people 2 to 3III Resembles vibrations caused by heavy traffic 3 to 4IV Felt by people walking; rocking of free standing objects 4V Sleepers awakened; bells ring 4 to 5VI Trees sway, some damage from falling objects 5 to 6VII General alarm, cracking of walls 6VIII Chimneys fall and some damage to building 6 to 7IX Ground crack, houses begin to collapse, pipes break 7X Ground badly cracked, many buildings destroyed. Some landslides 7 to 8XI Few buildings remain standing, bridges destroyed. 8XII Total destruction; objects thrown in air, shaking and distortion of ground 8 or greater
• 9. TASK: SORTING• Using the following statements, sort them into which best describes the scales.• Here
• 10. Richter ScaleIntensity Magnitude Observations (Mercalli)(Mercalli) (approx. comparison)I No effect 1 to 2II Noticed only by sensitive people 2 to 3III Resembles vibrations caused by heavy traffic 3 to 4IV Felt by people walking; rocking of free standing objects 4V Sleepers awakened; bells ring 4 to 5VI Trees sway, some damage from falling objects 5 to 6VII General alarm, cracking of walls 6VIII Chimneys fall and some damage to building 6 to 7IX Ground crack, houses begin to collapse, pipes break 7X Ground badly cracked, many buildings destroyed. Some landslides 7 to 8XI Few buildings remain standing, bridges destroyed. 8XII Total destruction; objects thrown in air, shaking and distortion of ground 8 or greater
• 11. TASK: WATCH THESE CLIPS• Tachoma, Japan earthquake: Here• Chilean earthquake: Here• Kashima, Japan earthquake: Here• Tokyo, Japan earthquake: Here• Maryland, USA earthquake: HereWhich scale was the most easy to use? Why?
• 12. EXAM PRACTISE• Describe 2 differences between the Mercalli and Richter scale. (2 marks)One difference is …………A second difference is that……………
• 13. LEARNING OBJETIVES• Know the differences between the Mercalli (intensity) and Richter (magnitude) scales.• Explain how earthquakes occur with reference to the epicentre and focus of earthquakes.
• 14. EPICENTRE• Epicentre on google earth: here• Interactive : Here
• 15. EPICENTRE AND FOCUS
• 16. EXAM QUESTION• Outline a difference between the focus and epicentre of an earthquake. (2marks)
• 17. LEARNING OBJETIVES• Know the differences between the Mercalli (intensity) and Richter (magnitude) scales.• Explain how earthquakes occur with reference to the epicentre and focus of earthquakes.