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In 1934, a California Geologist named Charles F. Richter came up with a better idea. His method, known as the "Richter Magnitude Scale" uses a scientific logarithm to determine the magnitude of an earthquake by measuring the acceleration of the ground during a shock. This method, of course, requires the use of scientific instruments to measure the variables used in the formula.
The Richter Scale, as it is now widely known, is an open-ended scale. That is to say there is no top end to it. However, the magnitude of the strongest quake ever recorded (Chili, 1960) was around 9.0 on Richter's Scale. As a sidebar, it has been estimated that it would take an explosion of 200 million tons of TNT to match the energy expended in that quake.
The interesting thing about the Richter Scale is that for each incremental rating of one that an earthquake scores, its strength or energy is actually multiplied by a factor of 10. So a 6.0 quake has 10 times the energy of a 5.0 quake. (The amount of energy that theoretically would be released in a magnitude 12 earthquake would equal 1 trillion tons of TNT and would be sufficient to fracture the earth in half through its center!)
The Richter Scale
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Magnitude
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Effects
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Estimated Number Per Year
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less than 2.5
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Usually not felt, but can be recorded by seismograph
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900,000
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2.5 to 5.4
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Often felt but only causes minor damage
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30,000
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5.5 to 6.0
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Slight damage to structures
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500
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6.1 to 6.9
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May cause much damage in populated areas
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100
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7.0 to 7.9
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Major earthquake; serious damage
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20
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8.0 or greater
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Great earthquake; can totally destroy communities near the epicenter
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One every 5-10 years
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Definitions and Introduction | The Modified Mercalli Intensity Scale | The Richter Magnitude Scale | Colorado's Seismic Risk | Secondary Hazard Events | Survival Tips
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