21. How does the Richter Magnitude Scale calculate its measurements?*1 pointEyewitnessesAmount of damage causedThe amount of time the earthquake lastedThe strength of the seismic waves recorded by a seismograph machine

The Richter Magnitude Scale calculates its measurements based on the strength of the seismic waves recorded by a seismograph machine. Here are the steps:

1. An earthquake occurs and seismic waves are produced. These waves travel through the Earth and are recorded by seismographs.

2. The seismograph records the amplitude of the seismic waves. The amplitude is the height of the waves on the seismograph.

3. The Richter scale takes the logarithm of the amplitude. This is because the energy released by an earthquake increases exponentially with the amplitude of the seismic waves.

4. The distance between the seismograph and the earthquake is also taken into account. The further away the seismograph is from the earthquake, the smaller the amplitude of the seismic waves it records.

5. The final magnitude of the earthquake on the Richter scale is calculated by combining the logarithm of the amplitude with a correction factor for the distance.

So, the Richter Magnitude Scale does not rely on eyewitness accounts, the amount of damage caused, or the duration of the earthquake. It is purely a measure of the energy released by the earthquake, as recorded by a seismograph.