Analysis of Time Dynamical Features in Intraplate Versus Interplate Seismicity: The Case Study of Iquique Area (Chile)

Abstract

The intraplate and interplate seismic catalogues of Iquique (Chile) area were investigated by using seismological (b value of the Gutenberg–Richter law), fractal (Allan Factor and detrended fluctuation analysis) and topological (Horizontal Visibility Graph) methods. The two catalogues show different stress state indicated by the different b value, larger for the intraplate seismicity. The interplate seismicity shows significant time-clustering behavior of the earthquake occurrence times at large time scales, while the time distribution of the intraplate earthquakes seems to be featured by random fluctuations without any significant sign of time-clustering. Different role seems to be played by aftershocks in the two investigated seismic zones, revealed by the different time distribution of the aftershock-depleted catalogue of the intraplate zone, which remains Poissonian for most of the time scales, and the interplate zone that still keeps its clustering phenomenon but at higher timescales, thus shortening its clustering time scale range. Furthermore, the interevent times of the interplate catalogue are characterized by persistent dynamics even after removing the aftershocks, while uncorrelated fluctuations characterize the behavior of interevent intervals of the whole as well as aftershock-depleted intraplate catalogue. Additionally, the magnitudes of both catalogues are characterized by time-reversibility before and after the aftershock removal; while the interevent times of intraplate catalogue change their status from time-irreversibility to time-reversibility after removing the aftershocks. The obtained results seem to evidence a different role played by the aftershocks in the intraplate and interplate zones, that needs to be further explored.