An earthquake at magnitude five on the Richter Scale is how many times more shaking amplitude than one at magnitude four?

The Richter magnitude scale (ML, also Richter scale) assigns a magnitude number to quantify the size of an earthquake. The Richter scale, developed in the 1930s, is a base-10 logarithmic scale in order to cover the huge range of earthquakes. It defines magnitude as the logarithm of the ratio of the amplitude of the seismic waves to an arbitrary, minor amplitude, as recorded on a standardized seismograph at a standard distance.

As measured with a seismometer, an earthquake that registers 5.0 on the Richter scale has a shaking amplitude 10 times greater than an earthquake that registered 4.0 at the same distance.

In the United States, the Richter scale was succeeded in the 1970s by the moment magnitude scale. The moment magnitude is currently used by the US Geological Survey to describe magnitudes for all earthquakes