Mechanical waves are the product of a perturbation of a medium caused very often by a vibration. What is characteristic of the different types of mechanical waves is that their propagation does not involve a real displacement of the particles of the medium. The particles just oscillate a bit around their initial position, returning to the starting point as the energy goes away. That means that mechanical waves' propagation involves a displacement of energy and not a displacement of the substance of the medium where they propagate.
From the point where the initial vibration occurs mechanical waves will propagate in all directions, loosing intensity with the distance until the energy dissipates. That's why we see rings on the water when rain or whatever object falls in it.
A little note about frequencies: mechanical waves lose intensity with the distance and when encountering surfaces, being the trebles the range of frequencies suffering the most. Think of a concert of pop or rock music you are going to: as you get closer you'll be able to hear more and more instruments. From afar, you won't hear anything but the bass.