Step-by-step explanation:
the amplitude is the height of the wave.
like with sound - the further away you are, the lower the volume of the sound (as the sound volume is the indicator of the amplitude of a sound wave, or the brightness of a light is the indicator of the amplitude of a light wave).
the same for any other type of wave (like the seismic wave of an earthquake).
so, the larger the distance, normally the smaller the amplitude.
