Natural Hazards and Earth System Science www.nat-hazards-earth-syst-sci.net 1561-8633 1684-9981 1 3 2001 10.5194/nhess-1-145-2001 http://www.nat-hazards-earth-syst-sci.net/1/145/2001/ http://www.nat-hazards-earth-syst-sci.net/1/145/2001/nhess-1-145-2001.html http://www.nat-hazards-earth-syst-sci.net/1/145/2001/nhess-1-145-2001.pdf 145 158 0000-00-00 The pecularities of shear crack pre-rupture evolution and distribution of seismicity before strong earthquakes D. Kiyashchenko V. Troyan Physics Department, St. Petersburg State University, 1 Ulianovskaya Street, St. Petersburg, 198 504, Russia Several methods are presently suggested for investigating pre-earthquake evolution of the regions of high tectonic activity based on analysis of the seismicity spatial distribution. Some precursor signatures are detected before strong earthquakes: decrease in fractal dimension of the continuum of earthquake epicenters, cluster formation, concentration of seismic events near one of the nodal planes of the future earthquake, and others. In the present paper, it is shown that such peculiarities are typical of the evolution of the shear crack network under external stresses in elastic bodies with inhomogeneous distribution of strength. The results of computer modeling of crack network evolution are presented. It is shown that variations of the fractal dimension of the earthquake epicenters’ continuum and other precursor signatures contain information about the evolution of the destruction process towards the main rupture.