Answer:
It is detected by a seismograph.
It is measured by the Mercalli scale.
It is based on the size of seismic waves.
Step-by-step explanation:
The earthquake's magnitude can be described as follows.
1. It is detected by a seismograph.
Magnitude follows the logarithmic scale of base 10. Alternatively, any motion caused by the earthquake increases by 10 times on a seismograph.
2. It is measured by the Mercalli scale.
This scale follows the observations of survivors or witnesses of the earthquake.
3. It is based on the size of seismic waves.
Richter scale takes into account the strongest wave recorded by the seismometer and seismometer's proximity to the earthquake.