# The Richter and Mercalli Scale

Refers to AQA A2 Geography

Plate Techtonics and Assosiated Hazards

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• Created by: Bethany
• Created on: 01-04-14 17:01
• The Richter and Mercalli Scale
• THE RICHTER SCALE
• A LOGARITHMIC Scale
• This means that an event measured a 7 on the scale is TEN TIMES GREATER than one measuring 6 on the scale.
• Energy release is proportional to magnitude.
• For eact unit increase on the scale, energy released increases approx. 30 times.
• Past earthquakes on the scale
• Largest ever measured on scale was Great Chilean Earthquake of 1960, which measured 9.5.
• Largest ever recorded UK earthquake was 4.8 on the scale, large for the UK but small compared to Haiti Earthquake, for example, with a magnitude of 7.0.
• THE MERCALLI SCALE
• Considers both the intensity of an event AND its impact.
• Level I would be equivelent to two on the the Richter Scale. Detected by seismometers but felt by very few, if any. No damage caused.
• Comparisons to Richter scale would depend on the location of the earthquake, hence influencing its impacts.
• The top level is Level XII. This represents total destruction with the ground seen to shake. This would be equivlent to approx 8.5 on the Richter Scale.
• Comparisons to Richter scale would depend on the location of the earthquake, hence influencing its impacts.
• WHICH IS BETTER?
• Problems with the Mercalli Scale.
• No use in an uninhabited area such as a desert where there is little human damage
• Statements such as resembling heavy traffic only apply if a person has felt heavy traffic, or what they feel is heavy traffic, which may differ if they live in a rural area.
• Impacts vary in different areas, so may be multiple values for the same earthquake.
• Somewhat SPECULATIVE
• Problems with the Richter Scale
• Doesn't take into account amount of damage; an earthquake which may cause collosal damage in one place would cause little damage in an uninhabited area.
• Judgement
• The Richter Scale allows easy comparisons of earthquakes which are not speculative regardless of location, and is a mathematical calculation, not a rough category.