Statistical analysis of seismic data on earthquakes in the area of the Vrancea focus

The present contribution deals with distribution laws of the earthquake's magnitude, the number of earthquakes (by modelling the generation process as a Poisson process) and the time interval between two successive earthquakes. The most important conclusion arrived at is that in the area of the Vrancea focus the distribution of the magnitudes is lognormal and brings forth a frequency-magnitude relation of the form log λ ( Μ ) = a + b log M + c ( log M ) 2 , not a linear one. A correlation between the magnitude and the time interval of two successive earthquakes is considered and a series of seismic indices are introduced.