The waveform similarity approach to identify dependent events in instrumental seismic catalogues

摘要

In this paper, waveform similarity analysis is adapted and implemented in a declusteringprocedure to identify foreshocks and aftershocks, to obtain instrumental catalogues that arecleaned of dependent events and to perform an independent check of the results of traditionaldeclustering techniques.Unlike other traditional declustering methods (i.e. windowing techniques), the applicationof cross-correlation analysis allows definition of groups of dependent events (multiplets) characterizedby similar location, fault mechanism and propagation pattern. In this way the chain ofintervening related events is led by the seismogenetic features of earthquakes. Furthermore, atime-selection criterion is used to define time-independent seismic episodes eventually joined(on the basis of waveform similarity) into a single multiplet. The results, obtained applyingour procedure to a test data set, show that the declustered catalogue is drawn by the Poissondistribution with a degree of confidence higher than using the Gardner and Knopoff method.The declustered catalogues, applying these two approaches, are similar with respect to thefrequency–magnitude distribution and the number of earthquakes.Nevertheless, the application of our approach leads to declustered catalogues properly relatedto the seismotectonic background and the reology of the investigated area and the success ofthe procedure is ensured by the independence of the results on estimated location errors of theevents collected in the raw catalogue.