Lets just for a second Speculate that the Vibrations aren't a bug...but maybe something to do with April Fools. Everyone is so desperately wanting something to happen... What if It's already begun?! Put on the tinfoil hats yo!

Leading rumor is a meteor hitting Tilted, and what happens with something that big starts closing in? Everything starts shaking like crazy. I'm calling it has to do with the meteor!

Or A more practical reason is for people playing with no sound.

A lot of people are deducing that it has to do with being in close proximity to another player. With all of the posts here of sneaky squads sneaking up on people...it is within reason. Has anyone checked the menu for a toggle? (I'm at work or I would)

That being said there seems to be an equal amount of people that just get vibrations by themselves out in the middle of nowhere....so who knows?