Conventional and Fractal Variogram Based on Time—Space Analysis of Seismicity Distribution—Case Study: Algeria Seismicity (1673-2010)

摘要

Geostatistics belongs to the wide class of statistical methods. It is used and applied to analyze and predict the values associated with spatial or spatio-temporal phenomena such as seismological events. Thus, in addition to its adaptability to perform spatial data analysis based on the principles of variography, many other methods more representative of the spatial distributions of the epicentres have been experimented. The unidirectional or isotropic fractal variogram associates the criterion of variance with the fractal dimension which is a better descriptive parameter of the spatial organization of events. The same analysis procedure carried out through a directional or azimuthal variogram introduces the context of a preferential direction of earthquake evolution. Moreover, b-value is a privileged seismological parameter that can be studied alone or in combination with other more advanced geostatistical analysis factors such as fractals, fractal dimensions and the anisotropic variogram. All these concepts were used as methodology for a protocol of analysis of the catalog of the Algeria seismicity including 1919 events for the period extending from 1673 to 2010. This catalog is provided by the compilation of partial catalogs synthesized by the CRAAG (Research Centre in Astronomy, Astrophysics and Geophysics).