Kala's awakening is felt all over the world (and tanked at ground zero by Heruka Ajna). As everyone felt it, and we see the ground visibly shake, that would be a VI, or strong.
Final Results
Kala's awakening = 108 megatons
Remember, this just from Kala waking up, not nearly her full strength. Heruka Ajna tanks it at ground zero, though is sent flying hundreds of miles away.