The Richter Scale, developed by CalTech scientist Charles Richter in the 1930s, quantifies how much the ground shifts during a quake. The Richter scale is logarithmic; each one-point increase represents a ten-fold jump in the amplitude of an earthquake's seismic waves, and a 30-fold increase in the amount of energy released. A 7.0 quake, for example, has many times the destructive energy of a 6.0. A 2 or 3-magnitude quake is big enough to be felt by people, and generally quakes have to be at least 5.0 to cause damage. 6.0 or higher is considered a major earthquake, and quakes of 7 or higher can cause loss of life and property on a catastrophic level. The only earthquake in the 20th Century to reach or exceed 9 on the Richter Scale was the May 1960 earthquake in Chile, which registered 9.5. The greatest loss of life came, however, from the 8.2 quake which struck China in July 1976, killing nearly 250,000 people.