Fractal analysis of shallow and intermediate-depth seismicity of Hindu Kush

Statistical seismology helps in understanding the underlying seismicity properties using some wellknown scaling relations that characterize different aspects of earthquake distribution. Among these scaling relations the Hurst (H) exponent has been extensively used to demonstrate the fractal properties of earthquake activity. In this study, we investigate the long-range correlations of seismicity parameters of shallow and intermediate-depth earthquakes of the Hindu Kush region using H statistics. The H index is computed for time window of 200 events with a slide of 15 data points on a complete and de-clustered catalog (1960-2007) prepared by Rehman et al. (2017). The long-range characteristics of seismicity are explored using size, time, space, depth and energy release. For shallow seismicity, the persistency (0.5 <= H <= 1) is found to be dominant except in a few periods of random walk. Contrary to this, intermediate-depth events show an evident change in H index around the time of major seismic events. Furthermore, the comparison of fractal behaviour of shallow and intermediate-depth seismicity confirms a notable difference in statistical properties. Our results also serve as a baseline study for seismicity analysis using multi-fractal approach for this region. (C) 2019 Elsevier Ltd. All rights reserved.