[noob] Except 'heavy hitter' what else scales the dmg of earthquake? Is it affected by DoT or critical damage?

My question is very basic , what specifically causes earthquake to deal more damage ?
- critical strike dmg ?
- DoT rings/amulet ? Isn't earthquake considered a DoT ability?
- does overpower dmg affect earthquake somehow?

What is the main way to scale earthquake damage except increase my primary Strength value and the codex aspects?