Abstract

Using the seismic entropy method, the nucleation of the recent earthquake of March 25, 2020 (M = 7.5) east of the Kuril Islands is studied. This earthquake, by analogy with the doublet of the strong earthquakes of 2006–2007 in the Central Kurils, revealed the frontal system in the Northern Kuril–Kamchatka region. The frontal seismic systems are located in the central segments of the Kuril–Kamchatka arc and are separated from the rear systems by an oceanic trench. These seismic systems make it possible to describe the preparation of unusually strong rare earthquakes in the Pacific Plate before the subduction zone, to reveal the dynamics of slow stress accumulation over decades, to schematically simulate the deformations of interacting plates before strong earthquakes, and to conduct a comparative analysis of these deformations in the Central and Northern Kurils. The frontal and rear seismic systems in the Northern Kuril–Kamchatka region with a threshold magnitudes of 8.4, 7.8, 7.4, and 6.6 are described in detail. It is shown that in a megaseismic system with a threshold magnitude of 8.4, large entropy is accumulated and a megaearthquake with magnitude M ≥ 8.7 is prepared. A comparative analysis with the preparation trajectory of the destructive Kamchatka earthquake of 1952 shows that it may occur before 2029. Monitoring of seismicity based on the identified hierarchy of rear and frontal systems will improve the quality of forecasts and reveal the role of very rare strong earthquakes in the interaction of plate segments in the subduction zone.

中文翻译：

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利用地震熵方法检测2020年3月25日东千岛群岛强地震的特征

摘要

使用地震熵方法，计算了2020年3月25日（M = 7.5）在千岛群岛以东。类似于2006-2007年千岛中央大地震的两次地震，这次地震揭示了北千岛-堪察加地区的额叶系统。正面地震系统位于千岛—堪察加弧线的中段，并通过海洋海沟与背面系统分开。这些地震系统使得能够描述俯冲带之前太平洋板块异常强的罕见地震的制备，揭示数十年来缓慢的应力积累动态，示意性地模拟强地震之前相互作用板块的变形并进行对中千岛和北千岛的这些变形的比较分析。详细描述了北千岛-堪察加半岛地区的前，后地震系统，其阈值震级分别为8.4、7.8、7.4和6.6。结果表明，在阈值为8.4的大地震系统中，积累了较大的熵，震级为6.3级的特大地震。中号≥8.7制备。与1952年堪察加破坏性地震的准备轨迹进行的比较分析表明，地震可能发生在2029年之前。基于确定的前后系统层次结构的地震活动监测将提高预报的质量，并揭示非常罕见的强震的作用在俯冲带板块的相互作用中