One note, is that other than the knockdown, Earthquake is designed to be a PvE AoE spell for specific encounters. Their "philosophy" if you will is for 3 types of PvE fights. The single target boss fight, where no multi target or aoe spells are used, then there's the 3-5 mob trash packs, where we used to just use AOE, but now they want us to burn one at a time, and use CC. Then there's the massive packs of tiny mobs, and this is what earthquake was meant for. Think of the trash in ICC, those large packs of skeletons. I was solo boxing a shammy in icc25, and on a few trash packs, I was hitting 17k DPS, and topping the charts.

Bottom line is don't expect it do do massive damage against a handful of targets, it's meant for doing damage to dozens of targets.