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This means that we have to understand two factors that characterize impact. Magnitude is an absolute measurement of the size and power of an event. When we speak of a Moment Magnitude 6.5 earthquake, a Category IV hurricane, an old Fujita 3 tornado, a 70,000 barrel oil spill, or a railway accident that kills 152 persons, we are attributing magnitude to the event. Intensity is a measurement of how the effects of the event are felt in a specific place. To some degree the Saffir-Simpson (hurricane) and Fujita (tornado) scales do this in that they provide descriptions of the levels of damage and effects that will occur at the point of greatest impact. However, the most commonly used intensity scale is probably the Modified Mercalli Intensity scale for earthquakes. This scale allows the plotting of lines of equal intensity in earthquakes, characterizing the extent of impact within these lines.