My fanon: Originally she was just making an educational video with what she thought would be a fairly typical eruption as a visual aid. She wasn’t expecting that he eruption would turn out this explosively. Since “The sound of a great scientific discovery being made not usually ‘Eureka!’ but rather ‘Huh… that’s odd…’.” as soon as her startlement passes she is going to cast the requisite heat, acid, and toxin proofing spells and teleport over as fast as possible for a look. She will be frustrated when she can’t quite summon all of the instruments she wants, and either about whether to go back to get more, or stay to keep an interrupted period of observation going.

(After that I couldn’t decide what would happen next.)

Quickly, sacrifice the Equestria Girls!

“So, uh, my lair has a little heating problem…”

Twilight: “Oopsy. My bad.”