I think one needs to try to keep some standards to prevent exaggeration. Approved USGS usage is:

Great = 8+
Major = 7-7.9
Strong = 6-6.9
Moderate = 5-5.9

etc

As to effects, one can use the useful headings from the EMS intensity scale:

Strong = 5
Slightly damaging = 6
Damaging = 7

etc

• EMS degrees