Please try again later. Ahmed Rashid, former Pakistani revolutionary, journalist and an expert on Taliban, explains why Pakistan is in a such a mess. He lists the factors that led Pakistan to the situation it is in right now.lease try again later. Ahmed Rashid, former Pakistani revolutionary, journalist and an expert on Taliban, explains why Pakistan is in a such a mess. He lists the factors that led Pakistan to the situation it is in right now.
Body waves travel through the interior of the Earth. On the other hand, surface waves propagate only at the interface between two different media, like the interface between Earth and atmosphere (i.e. the surface of the Earth).Body waves are of two types: Primary waves (also called P-waves, or pressure waves) and Secondary waves (S-waves, or shear waves).n the other hand, surface waves propagate only at the interface between two different media, like the interface between Earth and atmosphere (i.e. the surface of the Earth). Body waves are of two types: Primary waves (also called P-waves, or pressure waves) and Secondary waves (S-waves, or shear waves).
Definition of a Wave. Webster's dictionary defines a wave as: The most important part of this definition is that a wave is a disturbance or variation which travels through a medium. The medium through which the wave travels may experience some local oscillations as the wave passes, but the particles in the medium do not travel with the wave.