| Earthquakes can be measured in several ways. The first way is to describe the earthquake's intensity. Intensity is the measure, in terms of degrees, of damage to the surface and the effects on humans. Intensity records only observations of effects on the crust, not actual ground motion or wave amplitudes which can be recorded by instruments. While intensity helps to determine how large of an area was effected, it is not an accurate measure of the earthquake for many reasons. Two such reasons are: only the effect on an area showing the greatest intensity is reported, which can imply a greater or lesser intensity than what actually occurred, and the way in which seismic waves travel varies as they pass through different types of rocks, so some areas near by may feel nothing because they are built on faulted rock, while other areas quite a distance from the foci will feel the effects because they are built on compact homogenous rocks. The second type of measurement is the magnitude of the earthquake. Magnitude does not depend on population and effects to ground structures, but rather on wave amplitude and distance. Magnitude is determined using mathematical formulae and information from seismograms. One such magnitude scale is the Richter scale. This magnitude scale is logarithmic, meaning each step in magnitude is exponentially greater than the last. | |
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