Seat Airbag: Operation
WARNING: This page is about a different car, the 2006 Chrysler PT Cruiser. However, it is still accessible from the selected car via links, so may be relevant.
When supplied with the proper electrical signal, the inflator seals the hole in the airbag cushion so it can discharge the compressed gas it contains directly into the cushion. Upon deployment, the seat back trim cover will tear open and allow the seat airbag to fully deploy between the seat and the door.