It takes a while to cast earthquake. On the other hand, you can near insta-cast shadow jump. As soon as I see the earthquake or meteor storm power words overhead, I have plenty of time to shadow jump to safety.
If you avoid the damage, you avoid being revealed. That's probably better than putting 45 extra skill points into stealth. I'm not even sure that 120 stealth gives you a better chance of not being revealed, except with regards to detect hidden.