On the propagation of tremors over the surface of an elastic solid

The paper treats of the propagation of vibrations over the surface of a “semi-infinite” isotropic elastic solid, i. e ., a solid bounded only by a plane. For purposes of description, this plane may be conceived as horizontal and the solid as lying below it, although gravity is not specially taken into account. The vibrations are supposed due to an arbitrary application of force at a point. In the problem most fully discussed this force consists of an impulse applied normally to the surface; but some other cases, including that of an internal source of disturbance, are also (more briefly) considered. Owing to the complexity of the problem, attention has been concentrated for the present on the vibrations as they manifest themselves at the free surface; the modifications which the latter introduces into the character of the waves propagated into the interior have accordingly not been examined minutely.