Natural disasters in Japan shaking we call an earthquake. Earthquakes can cause shaking that could last seconds or minutes. Besides that, there may be several earthquakes over a period ranging from hours to weeks called aftershocks, and the magnitude of the following tremors will decrease with time. It is important to know the earthquake magnitude because it can be the clue if there will be any aftershocks. Because of that, magnitude can be measured on the Richter scale, invented by Charles F. Richter in 1934. The Richter magnitude is calculated from the amplitude of the largest seismic wave recorded for the earthquake. In the
Order of magnitude Order of magnitude An order of magnitude is an approximate measure of the number of digits that a number has in the commonly-used base-ten number system. It is equal to the logarithm (base 10) rounded to a whole number. For example, the order of magnitude of 1500 is 3, because 1500 = 1.5 × 10. Differences in order of magnitude can be measured on a base-10 logarithmic scale in “decades” (i.e., factors of ten). Examples of numbers of different magnitudes can be found at Orders of magnitude (numbers). Generally, the order of magnitude of a number is the smallest power