[quote=@Legend]
<Snipped quote by Audacious>

What phenomena would induce a concerning level of activity?
[/quote]

We tend to be concerned if there's activity at all. But it can, and usually is, dangerous and needs to be managed before someone incapable of manipulating them gets themselves or others hurt. And that can happen at the smallest level... That said, a number of things could. A highly concentrated presence of an aspect of nature in a place where it isn't natural or forced can spawn elemental energy that then continues to grow as a self perpetuating feedback effect, for example.