Abstract
The stability and instability of two collinear shear cracks were investigated theoretically. When instability occurs in two pre-existing cracks, the cracks coalesce spontaneously and a large-scale crack is formed. Many seismological observations suggest the occurrence of this kind of rupture in the earth. Specific fracture energy or stress-drop is assumed to be inhomogeneously distributed. It is shown that the mode of coalescence has great diversity and is sensitive to the distribution of stress-drop or specific fracture energy. This diversity will be closely related to the diversity of earthquake rupture processes.
In this paper we specifically investigate the mechanism of generation of slow earthquakes and fault creeps along the San Andreas fault system. Our source model developed in the present paper satisfactorily explains observations for the above rupture phenomena. Our source model also explains, in a unified fashion, the existence of two distinct types of fault creeps, that is, stable continuous creep and propagating episodic creep, along the San Andreas fault system.
