Analogues of gravitational and rigid waves

The paper presents the results of an investigation of the wave equation describing the processes of wave propagation from accelerating moving gravitational masses. It is stated that a wave can propagate both in a rigid medium (Earth core, ocean´s bottom, water, atmosphere) and in a medium without rigid interactions. Mathematical analogues between rigid and gravitational waves are found out. The approximate formulae for the velocity of gravitational wave propagation caused by underwater earthquakes are suggested. It is shown theoretically that the wave equation under investigation is true not only for distances close to the Earth but for rather far distances from the Earth up to the Moon. Experimental research carried out not far from the Earth and ocean surfaces proves that gravitational waves really exist and propagate with the finite velocity.