I usually point out that most loss of life and property has been due to the collapse of antiquated and unsafe structures, mostly of brick and other masonry.

We would have been happy if we could have assigned just three categories, large, medium, and small; the point is, we wanted to avoid personal judgments. It actually turned out to be quite a finely tuned scale.

Emphasis was usually put on the horizontal acceleration factor, for the simple reason that ordinary structures have a built-in safety factor for the vertical component; that is, gravity.

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.

My amateur interest in astronomy brought out the term 'magnitude', which is used for the brightness of a star.

For example, some stars put out large amounts of energy in the infrared part of the spectrum, so that this can produce a different relative magnitude rating than using light energy from the middle of the spectrum.