The Richter scale is not very accurate in measuring these larger earthquakes and today scientists use the Moment Magnitude Scale which uses the same logarithmic scale but which more accurately measures the strength of larger earthquakes. The largest earthquake ever recorded was in Chile in 1960, which measured 9.5 on the Richter scale. Earthquakes measuring upwards of 7 are less frequent but very powerful, and can cause a lot of destruction. In the countries of the former Soviet Union has been used scale independent energy class KR, defined as the logarithm of the seismic energy ER, highlighted by.
Earthquakes measuring 1-2 on the scale happen regularly, and they are so small that people cannot feel them. It is logarithmic which means, for example, that an earthquake measuring magnitude 5 is ten times more powerful than an earthquake measuring 4. In practice, readings from all observing stations are averaged after adjustment with station-specific corrections to obtain the M L value. A Richter scale is normally numbered 1-10, though there is no upper limit. The Moment magnitude scale is used to measure the size of earthquakes in terms of the energy released. The original formula is: 6 where A is the maximum excursion of the WoodAnderson seismograph, the empirical function A0 depends only on the epicentral distance of the station. Moment is a product of the distance a fault moved and the force required to move it. It is measured using a machine called a seismometer which produces a seismograph. The moment magnitude scale is based on the total moment release of the earthquake. From a theoretical point of view, this scale is reasonably re-liable since it is controlled by the fault size and the dislocation. The Richter scale measures the magnitude of an earthquake (how powerful it is). Kanamori (1979) to propose a new magnitude scale, namely moment magnitude, M W, dened by: M W 2 3 log M 0 10.7 (9) where M 0 is the seismic moment in dyn.cm. A Willmore seismometer measures earthquakesĮarthquakes, until recently, have been measured on the Richter scale.
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