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Abstract

The present number contains the papers read at the conference "Statistical and Tectonophysical Aspects of Seismicity" held from May 16 to 18, 1972, at the Central Earth Physics Institute of the German Academy of Sciences of Berlin, Jena branch, which serve as a basis for the discussions of the working group “Statistical Methods" within the subcommission "Seismicity of Europa" of the European Seismological Commission. In his opening speech the Director of the institute, Prof. STILLER, pointed out the importance of quantitative representation of seismicity for the complex problems of the project of geodynamics. The chairman of the European Seismological Commission, Prof. SAVARENSKY, Moscow, emphasized the statistical aspects of seismicity and explained the potentialities of physical interpretation of the laws established as well as their application to estimating the earthquake risk under various aspects. SCHENKOVÁ analysed the chronological succession of the earthquake of the northeastern Mediterranean in the period (1901, 1967) in the light of several models, from which an optimum model was found by the x²-test. PURCARU examined models of the frequency-magnitude dependence, e.g. those of UTSU and of OKADA, from the view-point of information theory. In two papers read by PANZA the seismicity of Italy including the fundamentals of representation was discussed, where the GUTENBERG-RICHTER magnitude-frequency relation is the underlying principle. Its coefficients were determined for the various seismotectonic units of Italy. Moreover, models of intensity distribution about the epicentres were set up for these regions. On the basis of seismic data going back as far as to the Birth of Christ maps of the seismic risk and of the active faults were then drawn up. Furthermore, PANZA demonstrated the great dependence of the magnitude value as obtained from the seismic surface waves on the focus depth of an earthquake in the earth's crust. MAAZ and PURCARU as well as NEUNHÖFER and MAAZ were concerned with logarithmically normal distributions of the frequency of earthquakes over the magnitude or energy, the determination of their coefficients and their confidence intervals. PROCHÁZKOVÁ pointed out the necessity of standardized methods for determining the parameters of the GUTENBERG-RICHTER frequency-magnitude distribution and gave recommendations in this respect. Two papers by ULLMANN and MAAZ established the connection of the seismicity function as energy flow density with the energy distribution in the focus by means of the BÅTH-DUDA formula for focus volumes and rendered a generalization of the seismicity function in which the inaccuracy of the focus coordinates is statistically considered.