Carrie uses her power to vibrate, by going though herself multiple times, and loosen the dirt around her. If her three seconds run out before the dirt is loose enough that she can safely power through it, she watches for the instamt her body catches up and does it again. Once the dirt is loose enough that no injury should be possible, she uses her power to quickly dig her way out. Also, her eyes and mouth are closed for this and she limits her breathing.
That's... not quite how your power works, you discover. Your movements after partially sinking back in are still limited by external factors - in this case, the dirt. It's like you rehearse the movement at first, and then your body executes it at double speed immediately afterward. In this case you, currently buried headfirst in the dirt along with your shoulders, arms forward and also below ground, do manage to wiggle out admirably well - your arms come free almost immediately, considerably earlier in the executed movement than in the intended one. Your body, now imbalanced in the originally intended movement, jerks to and fro, freeing your shoulders far earlier as well. These are the good news.
The bad news are, your powers do not let you adjust the rehearsed movement during its execution, a weakness that you become poignantly aware of when the preprogrammed wiggling manages to convey you into a state where you are currently have put most of your weight on your neck, and a little on your shoulders as well. It is only when your body catches up with you that you become aware that something has gone terribly wrong, namely that a very particular something in your spine appears to have gotten mildly traumatized. Only mildly, you see, because rather than kill you, it seems to have merely taken away the use of your legs. In the next second or so after your body stops its instruction, you seem to be free of the ground entirely, coming to a rest on the ground, taking a breath as you start to feel a little silly for having tried this, even if your method was as perfectly sound as it could be in a situation such as this.
"Ah, see, that was mild super speed right there. Told you, dude," One Eighty says with a measure of fascination. "Looks like she's getting it in bursts, not as a constant thing, though!"
"I'll take your word for it," Ilo replies, entirely unimpressed from the sound of it.
"Anyway, that's two capes already. Wonder if there's more?" One Eighty continues, tilting her head.
"Hazing a dumb kid not enough for you?" Ilo asks with but the merest hint of a questioning inflection.
"Shyeah, like hell it is. I wanna see something a little more impressive than this little cretin bitch and that jerkoff still on the bleachers, y'know? These people are supposed to be the hope of our generation!"
Steven watches Carrie getting flipped into the ground with a satisfied smirk, arrogance is a right that must be earned after all.
Turning his attention away from the actions of one eighty Steven inspects the branch carrie dropped, is it phasing through the floor or blurrimg any laws of reality anymore?
As it happens, it isn't. It's just split in half with a piece of it about the thickness of a hand missing in what you assume is its center of mass.
As it also happens, that stick is still on the ground next to the girl, who seems to have freed herself of the ground via the application of some kind of parahuman power, as One Eighty and Ilo, who are also still in plain view, observe. One Eighty, you notice, takes a few steps back nonchalantly as the girl wiggles free, even as she continues to speak with Ilo about how it'd be kind of cool if there were more interesting capes here tonight.
"R-really? ...H-how so?" Selina is a little nervous now, not sure what criticism was coming.
"Honestly, it sounds kinda cult-leaderish how she looks at the shy girl, don't you think? She sees her as someone she can mold to her liking when she gains her trust, then use her isolation and loneliness to strip her of any independence. An intelligent introvert in the early stages of social development is, like, the golden mark for people like this. I mean, just imagine how the breakup's going to be when school ends a year or two later," Rita says, shrugging periodically in an effort to not seem aggressive.