Given the unpredictability of the terror demon, Hermione had been focused on keeping an eye on where it would jump out from, meaning that she's caught completely off-guard by the tremors that suddenly shudder through the ground. "Oh!" is about all she manages to get out as her feet leave the ground, and she lands hard enough to scatter her senses, leaving her dazed and on her back and with no shield charm currently protecting her.

She's going to end up with more than a few bruises along her body, and that's only if she's lucky.