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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Seismic strain and seismogenic stress regimes in the crust of the southern Tyrrhenian region
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Seismic strain and seismogenic stress regimes in the crust of the southern Tyrrhenian region

机译：第勒尼安南部地区地壳的地震应变和发震应力状态

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An investigation has been performed to identify and characterize the seismic deformation zones active over the last decades in the region of Italy that has experienced the strongest seismicity during the last centuries. The study is based on the estimate of hypocenter locations, fault plane solutions, seismogenic stress and seismic strain tensor orientations carried out using the entire dataset of the national and local seismic networks, and the recently improved three-dimensional (3D) crustal velocity model of the study area. A series of simulation tests have been performed to evaluate the significance of the earthquake space distribution obtained and whether it was influenced by network geometry problems related to the sea and the lack of ocean bottom seismometers. In the sectors where hypocentral location was synthetically proved to be reliable, space distributions of earthquakes located with epicenter and focal depth errors less than 3 and 4 km, respectively, have been compared with local geology in order to identify seismogenic faults. The dataset of 32 fault plane solutions estimated with fault parameter errors less than 20° has been used to investigate space variations of seismogenic stress and seismic strain orientations over the study area. Stress was found to be uniform in the Messina Strait and southern Calabria where inversion of the available set of 11 fault plane solutions showed clear evidence of an extensional regime. The different orientations of the minimum compressive stress and strain found in this sector, together with the information available on local geology and tectonics, lead us to propose that the seismicity occurring over the last decades in the Messina Strait and southern Calabria was not in general produced at the main faults, but at minor faults activated by the main tectonic stress field acting in the area. To the west, in the sector including western Etna, the Nebrodi chain and the western Aeolian Islands, analysis of the available set of 16 fault plane solutions revealed a certain degree of stress heterogeneity with an apparent prevalence of north-south compression. This east to west change of stress-strain regimes is evaluated in the light of current hypotheses regarding the geodynamics of the study region.
机译：已经进行了一项调查，以识别和表征过去几个世纪以来在意大利地区经历过最强烈地震活动的近几十年来活跃的地震变形带。该研究基于对震源位置，断层平面解，震源应力和地震应变张量方向的估算，该估算是使用国家和地方地震网络的整个数据集以及最近改进的3D地壳速度模型进行的学习区。已经进行了一系列模拟测试，以评估获得的地震空间分布的重要性，以及它是否受到与海洋有关的网络几何问题以及缺少海底地震仪的影响。在综合证明震中位置可靠的部门中，震中和震源深度误差分别小于3 km和4 km的地震的空间分布已与当地地质进行了比较，以识别成地震断层。估计的断层参数误差小于20°的32个断层平面解的数据集已用于研究研究区域内的地震应力和地震应变方向的空间变化。发现墨西拿海峡和卡拉布里亚南部的应力是均匀的，那里可用的11个断层平面解集的反转显示了扩展机制的明确证据。在该领域中发现的最小压缩应力和应变的不同方向，以及有关当地地质和构造的信息，使我们提出，墨西拿海峡和卡拉布里亚南部近几十年来发生的地震活动通常没有产生在主要断层处，但在次要断层处由作用在该地区的主要构造应力场激活。在西部，在包括西部埃特纳火山，内布罗迪链和西部风成群岛的部分，对可用的16个断层平面解集进行分析，发现一定程度的应力非均质性，并且明显存在南北向压缩。根据有关研究区域地球动力学的当前假设，评估了应力-应变方式从东到西的变化。

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