Vibration usually begins when there is a build-up of stress in the earth's crust resulting in

Cultural convergence is the theory that two cultures will be more and more like each other a very notable example of this is around the u.s.-mexico border, where 

The answer i think is d

2. x2 + 8x + 12 = 0 to prove: x = -6 or x = -2

Answeroil-shale;