抄録
Following the way developed by Kostrov, the problem of propagation of longitudinal shear crack of finite length is discussed. It is assumed that the crack is developed at y=0 and its left edge is fixed. Assuming also constant stress drop τ0 along the crack, the x coordinate of the right edge of the crack X(t) is calculated as a function of time t. Essential non-dimensional parameters in the problem thus defined are a=L0/(βt0) and t0=πμT/(2βτ20), where L0, β, μ and T are initial crack length, shear wave velocity, rigidity and surface tension, respectively. Making use of seismological data of the Chile earthquake (May 22, 1960), T of the order of magnitude 1010 erg/cm2, an interpretation of which is given in the text, is obtained. After some additional calculations, it is concluded that, in order to stop the crack propagation abruptly, a geologically discontinuous surface, both sides of which have utterly no elastical connection, is necessary.
