Abstract
An elastic wave equation in a heterogeneous medium is solved by means of the WKB method. If it refers to the connection formula around a turning point, a solution that formally expresses a progressive wave, A(x)cos{ωt-k(x)x}, does not always satisfy the principle of energy conservation. The wave propagation with physical significance should be discussed using the structure of the heterogeneous medium intervening between two homogeneous half spaces.
