Complex sentence: Estimates for the energy released have varied from 9 kilotons, 100 kilotons, and 5 megatons, though most estimates place the energy at below 1 megaton.
Split into simpler sentences: Estimates for the energy released have varied from 9 kilotons, 100 kilotons, and 5 megatons. Though most estimates place the energy at below 1 megaton.