please help is the first time that it happens but the center of my cake sunked!!!!

Probably it's not done. (Not baked thru the middle.)

Do you have kids? Were they jumping around the oven? Or did you move the pan while it was still cooking? I get that problem, too, and usually it is because there is a lot of movement in the house. The vibrations makes the cake fall. It's a pain in the butt. HTH

Most likely reason is not baked enough. No vibrations should not effect it as Mike said.

What size pan were you using? I have baked a WASC cake in a 11X15 pan and it sank in the middle. After that cake, I started using an inverted flower nail and have never had that problem again. It will help the middle cook faster and would probably eliminate your problem.

Yeah, no way vibrations can do it...I have 2 kids that do that all the time and it never has fallen. Probably underbaked...try the flower nail if it's larger that an 8 in round

I have had that happen for no obvious good reason at all. It was cooked completely. So who knows. I decided it was a scrap cake. and boy was it yum.

if its a new recipe...suspect that it may have something to do with the altitude you are at.