This volume is a selection of the most significant papers Yu, V. Riz nichenko wrote during his 30-year career and concerns the development of fundamental problems of seismology. The book is in five parts. The first is devoted to source seismicity. It starts with a chapter on the "elementary unit" of seismicity, viz. the earthquake source. The size of an earthquake is in itself a significant problem in seismology and, is discussed here. The main energetic parameters of the source are consi dered, namely, seismic energy, magnitude, seismic moment, geometric size of the main fault, displacements...