“…As to the active rupture phase, the classical models by Kostrov [1964] and Madariaga [1977Madariaga [ , 1983 demonstrate singularities of the 'inverse square root' type, / 1 . A rigorous justification of the singularity in the framework of elasticity theory can be found in [Herrero et al, 2006]. Combining the two cases, we shall consider the source function around , and the spectral amplitude depends on radiation directivity via the stationary point.…”