科研之友
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摘要
In regions with long historical earthquake records, seismic hazard assessments are additionally challenged by the large uncertainties related to the available pre-instrumental data. A major source of uncertainty is the incompleteness of historical earthquake records. Therefore, an important step in seismic hazard assessment is the check of completeness for different intensity levels and the removal of aftershock sequences. Mainly two different approaches have been proposed for checking the completeness of seismic catalogues: the temporal course of earthquake frequency (TCEF), and a completeness check based on statistical analysis of the mean earthquake recurrence interval for varying time windows. We systematically compared the effects of the different methods on the Gutenberg-Richter relation (GR-relation), as well as the influence of removing fore- and aftershocks. %26lt;br%26gt;For that purpose we created and declustered a new composite catalogue for Austria, the Vienna Basin and a 100 km wide region outside the boundaries of Austria and Vienna Basin based on four different earthquake catalogues. We can show that the a- and b-values for the GR-relations derived from different completeness analyses depend on the correction method used. Corrections with the TCEF seem to produce lower a- and b-values. The Stepp method, on the other hand, excludes the highest intensity class (I-0 = X) 0 and tends to calculate lower a- and b-parameters. Based on these results, we prefer the latter. %26lt;br%26gt;Both completeness methods have further been applied to a subset of the composite catalogue corresponding to a source zone including the active Vienna Basin fault system. Comparison shows that completeness of the entire dataset is apparently overestimated.
- 出版日期2013
