Analyses of aftershock decay rates of Qotor Earthquakes on February ۲۳, ۲۰۲۰ in West Azarbaijan

The triggering mechanism of aftershocks is an aspect of earthquake occurrence, which is not fully understood. Also, another factor complicating the identification of causative effect of aftershock triggering is the delay in time of the aftershock events relative to the main shock. In this study the aftershock sequences of February ۲۳, ۲۰۲۰, Qotor earthquakes with MN۵.۷ and MN۵.۹ in West Azerbaijan are analysed. In this regard we investigated some well-known empirical scaling laws of aftershock's decay: the modified Omori’s law (MOL), Shcherbakov law or Generalized Omori–Utsu law, Reasenberg & Jones laws and Kisslinger stretched exponential descending law. Considering seismic activity of the studied region during two months revealed that the activity was very vigorous instantly after mainshocks occurrences. The number of events reduced remarkably during the first days. Also the sum of squares due to error (SSE) and the adjusted R-square statistics were examined to help determine the best fit. The SSE statistic is the least-squares error of the fit, with a value closer to zero indicating a better fit. The largest SSE found for MOL indicated a poor fit. The lowest SSE associated to the Shcherbakov law. However, the behavior of the fit beyond the data range made it a poor choice for extrapolation. The next best SSE value was associated to the Reasenberg & Jones and Kisslinger laws. As well, the R-squared values for the latter two laws found very similar

کلیدواژه ها:

Qotor earthquakes ، decay rate of aftershocks ، modified Omori’s law ، Omori–Utsu law ، Shcherbakov law ، Reasenberg & Jones law ، Kisslinger law