Abstract

Earthquakes in the Sea of Azov are quite commonplace. Until now, the idea of ​​their nature has focused on tectonic processes in the Earth’s crust. In our work, using morphotectonic analysis, we examined on a lithospheric scale the geodynamic situation in the collision zone of the East Black Sea Plate and the margin of the East European Platform, in order to show that not only in the crust, but also in the lower lithosphere, the necessary tectonic prerequisites exist for the accumulation of seismic energy with subsequent release in the form of earthquakes. Based on a case study of an earthquake that occurred on October 15, 2018, in the Sea of Azov, we showed the possible causes of its occurrence for two options of solving the seismological problem, obtained by the Geophysical Service of the Russian Academy of Sciences and including in the solution according to V.Yu. Burmin’s method. The following focal parameters are published on the Geophysical Survey website: latitude, 46.36; longitude, 37.18; depth, 5 km; m_b= 4.3. The focal parameters were obtained for the solution using the Burmin method: latitude, 46.42564; longitude, 37.24274; H = 133.4 km. The mechanisms of two solutions were constructed; for a source with a depth of 5 km, the focal mechanism was obtained: a reverse fault, with the source confined to the intersection of Kalmius-Dzhiginsky and the Main Azov faults; for 133.4 km, a strike-slip fault, with the source confined to the intersection of the Gubkinsky-Central Azov, Kalmius-Dzhiginsky, and the Main Azov faults. The constructed model of collision of the continental lithosphere of the East European Platform and the subducting East Black Sea Plate shows that under conditions of weak compressive forces from the side of the Arabian indenter, a pseudosubduction situation is formed, as a result of which shear stresses occur in the deformable frontal part of the continental lithosphere of the East European Platform, transitioning to a reverse fault along the line of shear. During this process, seismic energy is accumulated, accompanied by weak and moderate earthquakes, of a reverse-fault type for the earth’s crust in the region of the Azov Rise, and a normal-fault type in the lower part of the wedge of the continental lithosphere as a result of its destruction. Regional morphotectonic analysis did not allow us to choose the most probable focal mechanism for the earthquake. However, it is noteworthy that the results of our research have shown that the occurrence of deep earthquakes has all the necessary tectonic prerequisites, despite the well-established opinion of seismologists about the exclusively crustal location of earthquakes in this region.

中文翻译：

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2018年10月15日亚速海深震的可能原因

摘要

亚速海的地震很普遍。到目前为止，关于它们的性质的想法一直集中在地壳的构造过程中。在我们的工作中，通过构造构造分析，我们在岩石圈范围内检查了东黑海板块碰撞区和东欧平台边缘的地球动力学情况，以便不仅在地壳中而且在地壳中在较低的岩石圈，存在着积累地震能量并随后以地震形式释放的必要构造前提。基于2018年10月15日在亚速海发生的地震的案例研究，我们显示了解决地震问题的两种选择的可能原因，由俄罗斯科学院地球物理服务获得，并包括在根据V.Yu的解决方案中。布尔明的方法。在地球物理测量网站上发布了以下焦点参数：纬度46.36；经度，37.18; 深度5公里；m _b = 4.3。使用Burmin方法获得溶液的焦点参数：纬度46.42564；经度，37.24274; H= 133.4公里。构建了两种解决方案的机制；对于一个深度为5 km的震源，获得了震源机制：逆断层，震源局限于Kalmius-Dzhiginsky断层与Main Azov断层的交点；长达133.4 km，为走滑断层，震源仅限于古布金斯基-中央亚速号，卡尔米乌斯-迪吉金斯基和主要亚速号断面的交点。东欧平台大陆岩石圈与俯冲东黑海板块碰撞的构造模型表明，在阿拉伯压头侧向压力弱的条件下，会形成假俯冲的状态，其结果是剪切应力发生在东欧平台大陆岩石圈的可变形额部，沿剪切线过渡到反向断层。在此过程中，积累了地震能量，伴随着弱和中度地震，在亚速河谷地区的地壳为反断层型，在大陆楔形的下部为正断层型。由于岩石圈被破坏。区域构造构造分析不允许我们选择地震的最可能震源机制。但是，值得注意的是，尽管地震学家对这一地区的唯一地壳位置已建立了公认的观点，但我们的研究结果表明，深部地震的发生具有所有必要的构造前提。在亚速海地区，地壳是反向断层型，由于破坏，在大陆岩石圈楔形的下部是常断层型。区域构造构造分析不允许我们选择地震的最可能震源机制。但是，值得注意的是，尽管地震学家对这一地区的唯一地壳位置已建立了公认的观点，但我们的研究结果表明，深部地震的发生具有所有必要的构造前提。在亚速海地区，地壳是反向断层型，由于破坏，在大陆岩石圈楔形的下部是常断层型。区域构造构造分析不允许我们选择地震的最可能震源机制。但是，值得注意的是，尽管地震学家对这一地区的唯一地壳位置已建立了公认的观点，但我们的研究结果表明，深部地震的发生具有所有必要的构造前提。区域构造构造分析不允许我们选择地震的最可能震源机制。但是，值得注意的是，尽管地震学家对这一地区的唯一地壳位置已建立了公认的观点，但我们的研究结果表明，深部地震的发生具有所有必要的构造前提。区域构造构造分析不允许我们选择地震的最可能震源机制。但是，值得注意的是，尽管地震学家对这一地区的唯一地壳位置已建立了公认的观点，但我们的研究结果表明，深部地震的发生具有所有必要的构造前提。