A collision avoidance system including a plurality of inclinometers in offset wellbores and a processing unit for receiving a vibration signal from the inclinometers and determining a distance between the offset wellbore and a central wellbore based on the vibration signal. Also, a method of avoiding wellbore collisions by determining relative movement of a drill bit within a central wellbore including the steps of determining an original distance between the central wellbore and an offset wellbore, drilling in the central wellbore so that the drill bit moves a known distance with respect to the offset wellbore, capturing vibration readings during the drilling step, characterizing movement of the drill bit based on the drilling step, and calculating drill bit movement during drilling with respect to the offset wellbore based upon the characterizing step.