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A major earthquake, with magnitude Mw=7.3, struck the Northwestern part of Iranon November 12 2017, causing extended damage and casualties. The aftershocksequence is still ongoing, as testified by the two recent M6.4 (November 25, 2018)and M5.9 (January 6, 2019) events that occurred in the area more than one yearafter the mainshock. Thus, we investigate the aftershock sequence following thisearthquake, with the aim to understand whether it fits the classical laws of aftershocksoccurrence (e.g. the Omori Law), and to explore whether observed deviations from theselaws could provide some insights about the occurrence of possible further largeaftershocks. The Delta/Sigma method (Caccamo et al., 2005. Physics of the Earth and PlanetaryInteriors 153, 175–180), is used for this purpose, which is based on the observation ofpossible anomalies in the temporal decay of an aftershock sequence. Specifically, if the decaycan be modeled as a non-stationary Poissonian process, where the intensity function is equalto n(t) = K ⋅ gt + c)−p + K1, the number of aftershocks in a short time interval Δtis themean value n(t) ⋅ Δt, with a standard deviation Sigma2 = n(t) ⋅ Δt. Given the differencebetween observed and estimated number of events Delta = |Nobs-Ncalc|, it was found that,before the occurrence of large aftershocks, the Delta/Sigma ratio may reach rather highvalues, which can be considered as seismic anomalies. The Delta/Sigma method has beenapplied to several aftershocks sequences worldwide and different improvements of themethod have been developed during the last years, but it still requires rigorousand extensive testing to assess its capability in describing observed aftershocksoccurrence. The basic data used in this study have been extracted from the regional catalog of the IranianSeismological Center (IGTU catalog), which is available at http://irsc.ut.ac.ir/bulletin.php/.The IGTU catalog lists events with magnitude M≥2.5, recorded in the Iranian plateau andadjacent areas since 1 January 2006. Various experiments are carried out in order to verify if this method could identify thelarge aftershocks (with M≥4.8), which occurred in the region surrounding the Mw 7.3mainshock occurred in November 2017. Different input parameters and configurations of themethod are considered, in order to check the stability and statistical significance of theobtained results. The preliminary results of the study indicate that the application ofDelta/Sigma method to the Northwestern region of Iran, surrounding the Mw 7.3earthquake occurred in November 2017, could highlight the possible occurrence ofseveral significant aftershocks. Based on these results, the analysis is expanded toANSS global data provided by USGS, in order to assess the stability of the detectedpattern, which might provide relevant information for seismic risk assessment. [ABSTRACT FROM AUTHOR]