There's an air of slight desperation about the two installments that make up Supervolcano due to, I strongly suspect, some late decisions to try and increase the drama and realism. It starts by showing you a clip of the ending, as if to generate extra tension and interest, but merely reinforces a sense of predictability. There's a patchy and unsuccessful attempt to try and make it seem like a gritty 'docu-drama', by including interviews with the main characters talking straight into the camera: these are over acted and become slightly irritating. In general, the directing and acting is over done for much of the time, although a few of the cast do seem to be doing their best .
Supervolcano was definitely not super for me. There are far better, and more enjoyable, natural disaster movies out there to watch - like the comparable Dante's Peak for example.