M Agh-Atabai
Abstract
The Golestan province lies on one of the seismically active zones of the world. The occurrence of numerous historical and instrumental earthquakes in this area indicates its high seismic activity. Therefore, it is necessary to study its seismicity using different methods. In this research, the mono and ...
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The Golestan province lies on one of the seismically active zones of the world. The occurrence of numerous historical and instrumental earthquakes in this area indicates its high seismic activity. Therefore, it is necessary to study its seismicity using different methods. In this research, the mono and multifractal analyses have been applied for quantification of earthquakes pattern in the GolestanProvince. For this aim, the correlation dimension, generalized multifractal dimensions and singularity spectrum f (αq) have been calculated using the correlation integral and fix-mass methods. The epicentral analyses of earthquakes showed that their distribution has two scaling ranges with two different patterns and mechanisms controlling the earthquake pattern in these scales. It seems that the movements of small faults and fractures, which caused increasing the correlation dimension (1.84) and heterogeneity of multifractal structure, controlled the small scale. However, at large scale, the distribution of earthquakes is mostly controlled by the main structural trends, which in turn results in becoming almost linear their correlation dimension and also more homogeneous multifractal structure.
A. Zamani; M. Agh-Atabai
Abstract
The 31 March, 2006 earthquake with Mw=6.1 destroyed villages in the Darb-e-Astaneh (Silakhor) region of the Lurestan province. The epicenteral area of this earthquake lies near the Main Recent Fault (MRF) and its right lateral mechanism indicates that it belongs to this fault zone. The main shock was ...
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The 31 March, 2006 earthquake with Mw=6.1 destroyed villages in the Darb-e-Astaneh (Silakhor) region of the Lurestan province. The epicenteral area of this earthquake lies near the Main Recent Fault (MRF) and its right lateral mechanism indicates that it belongs to this fault zone. The main shock was followed by relatively large number of aftershocks. In this research, the aftershock sequence of this earthquake has been studied by measuring quantitative indices of coefficient of variations (CV), the exponent of the power spectral density function, and the generalized multifractal dimensions. The results reveal the presence of fractal structure in the temporal and spatial distribution of aftershock sequence. The multifractal behavior of the aftershock sequence indicates the clustering of the earthquake activity and the degree of the heterogeneity in the seismotectonic and geodynamic processes in the focal region. The results show that the multifractal dimensions of the aftershock sequence decreases and the multifractal dimensions of aftershock epicenters increases with time. It seems that these changes in the multifractal dimensions are related to the activity of secondary and sympathetic faults and changes in the tectonic stress regime of the region. The results also indicate that the multifractal method rather than monofractal approaches is a powerful tool for quantitative analysis of aftershock process's clustering behavior.