The seismic potential assessment for some seismogenic sources in the central northern Greece and its adjacent areas based on the maximum credible magnitude

Theodoros M. Tsapanos1, Simos D. Vlachos2 and Hariklia Ch. Georganta3

1Aristotle University of Thessaloniki, School of Geology, Geophysical Laboratory, 54124 Thessaloniki, Greece.

2 D. Kavafi 12, 54636 Thessaloniki, Greece.

3 Paraskevopoulou 9, 54640 Thessaloniki, Greece.

(Received 3 March 2002; final version accepted 18 July 2002)

Abstract: The identification and characterization of seismogenic sources are essential parts of seismic hazard evaluation because they enable forecasts to be made of locations, recurrence intervals and sizes of future large earthquakes. A difficulty is implicated in such studies because usually, the average repeat periods of large earthquakes on the seismogenic sources, are larger than the period covered by the data files used. In order to overcome such inconsistencies a procedure is applied, where parameters are estimated by the maximum likelihood method, by applying the Bayesian formalism and any additional geological or geophysical information (as well as all kinds of uncertainties) can be easily incorporated. The obtained parameters are the maximum credible magnitude mmax, the seismicity rate,λ, and the β parameter of the Gutenberg-Richter relationship. This procedure is capable of giving a realistic assessment of seismic hazard in areas of both low and/or high seismicity, including the cases where the catalogues are incomplete. Central Northern Greece and its surroundings is an area where large and catastrophic earthquakes occurred with high average repeat periods (e.g. source 35- see Fig.1b) or even worst there was no information concerned the seismicity of the source (e.g. source 36- see Fig. 1b). Bearing these in mind an effort is made to assess the seismic potential of the seismogenic sources of Northern Greece and its adjacent area based on the maximum credible magnitude mmax. Moreover their earthquake hazard evaluation, in terms of the probability of exceedance of a specified value of magnitude in T-years, is undertaken.

Keywords: Maximum Credible Magnitude, Bayesian Formalism, Seismogenic Sources, Seismic Potential, Central Northern Greece.