Rahimi-Majd M, Shirzad T, Najafi M N
Department of Physics, Shahid Beheshti University, 1983969411, Tehran, Iran.
Institute of Geophysics, Polish Academy of Sciences - 01-452, Warsaw, Poland.
Sci Rep. 2022 May 19;12(1):8364. doi: 10.1038/s41598-022-12362-7.
This paper is devoted to a phenomenological study of the earthquakes in central Alborz, Iran. Using three observational quantities, namely the weight function, the quality factor, and the velocity model in this region, we develop a modified dissipative sandpile model which captures the main features of the system, especially the average activity field over the region of study. The model is based on external stimuli, the location of which is chosen (I) randomly, (II) on the faults, (III) on the low active points, (IV) on the moderately active points, and (V) on the highly active points in the region. We uncover some universal behaviors depending slightly on the method of external stimuli. A multi-fractal detrended fluctuation analysis is exploited to extract the spectrum of the Hurst exponent of the time series obtained by each of these schemes. Although the average Hurst exponent depends slightly on the method of stimuli, we numerically show that in all cases it is lower than 0.5, reflecting the anti-correlated nature of the system. The lowest average Hurst exponent is found to be associated with the case (V), in such a way that the more active the stimulated sites are, the lower the average Hurst exponent is obtained, i.e. the large earthquakes are more anticorrelated. Moreover, we find that the activity field achieved in this study provide information about the depth and topography of the basement, and also the area that can potentially be the location of the future large events. We successfully determine a high activity zone on the Mosha Fault, where the mainshock occurred on May 7th, 2020 (M[Formula: see text] 4.9).
本文致力于对伊朗阿尔伯兹山脉中部地震进行唯象学研究。利用该地区的三个观测量，即权函数、品质因子和速度模型，我们开发了一种改进的耗散沙堆模型，该模型捕捉了系统的主要特征，特别是研究区域内的平均活动场。该模型基于外部刺激，其位置选择为：(I) 随机，(II) 在断层上，(III) 在低活动点上，(IV) 在中等活动点上，以及 (V) 在该区域的高活动点上。我们发现了一些略微依赖于外部刺激方法的普遍行为。利用多重分形去趋势波动分析来提取通过这些方案中的每一个获得的时间序列的赫斯特指数谱。尽管平均赫斯特指数略微依赖于刺激方法，但我们通过数值表明，在所有情况下它都低于0.5，这反映了系统的反相关性质。发现最低的平均赫斯特指数与情况 (V) 相关，即受刺激的地点越活跃，获得的平均赫斯特指数就越低，也就是说大地震的反相关性越强。此外，我们发现本研究中获得的活动场提供了有关基底深度和地形的信息，以及可能是未来大事件发生地点的区域信息。我们成功地在莫沙断层上确定了一个高活动区，2020年5月7日（震级[公式：见原文]4.9）的主震就发生在那里。
