With earthquakes, one has to deal with periods of vibrations that change within a rather narrow limits, while in engineering, the periods of soil fluctuations caused by various machines can fluctuate with a very wide range. For earthquakes, the oscillation period is measured by several seconds. It is advisable to use both scales for the accumulation of experimental material, which is very convenient, since they have the same number of divisions.
What actions should be taken with earthquakes