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Abstract

We analyse the fractal dimension of active fault systems versus the fractal dimension of earthquake epicentres in the Greater Caucasus, Altai-Sayan, Baikal, and Kamchatka Regions. In particular, for each of the four regional systems of active faults the box counting and correlation dimensions, D0 and D2, were computed based on the Active Faults of Eurasia Database (Bachmanov et al., 2017). The data permit distinguishing fractal dimensionality of the vertical, lateral and extensional displacement faults. The obtained regional values of D0 and D2 are compared to the regional distributions of the C-coefficient of the Unified Scaling Law for Earthquakes (USLE) that compliments to the a- and b-values of the classical Gutenberg-Richter relationship with C, an estimate of fractal dimension of earthquake epicentres at a given site. We used maps of the USLE coefficients in the selected four regions from (Kossobokov&Nekrasova 2018a, 2018b; Nekrasova&Kossobokov 2020, 2022). The comparison of fractal dimensions of active faults and earthquake epicentres has shown up higher values of dimensionality of regional fault systems, which evidence, presumably, a large number of locked, dormant, silent, or seismically inactive faults. From the viewpoint of instrumental/operational seismology, the tectonically active systems of blocks-and-faults reflect fragmentation of the lithosphere with a significant redundancy. In addition, for each of the four regions a cross-comparison of D0 and D2 versus C at the site of the observed largest earthquake is performed. The study is carried on in the framework of the Russian State Task of Scientific Research Works of IEPT RAS (0143-2019-0006).