I suggested that we might compare earthquakes in terms of the measured amplitudes recorded at these stations, with an appropriate correction for distance.

What emerged, of course, was that the magnitude scale presupposed that all earthquakes were alike except for a constant scaling factor. And this proved to be closer to the truth than we expected.

This is very similar to astronomy where different magnitudes are assigned to the brightness of an astronomical object, depending on the range of wavelengths being measured.

Incidentally, the usual designation of the magnitude scale to my name does less than justice to the great part that Dr. Gutenberg played in extending the scale to apply to earthquakes in all parts of the world.

Intensity like signal strength will generally fall off with distance from the source, although it also depends on the local conditions and the pathway from the source to the point.

If the assumptions used in calculating energy are changed, then this seriously affects the final result, even though the same body of data might be used.