Active stress field of the Southern Aegean Sea subduction area from fault-plane solutions on the basis of different stress inversion approaches

Kkallas Ch.; Papazachos C. B.; Scordilis E. M.; Margaris B. N.

摘要

We examine the active stress field of the Southern Aegean Sea subduction area from fault plane solution data, focusing on the variability resulting from the application of different stress inversion methods. The study area is characterized by a high seismicity level and has been struck repeatedly by large destructive shallow and intermediate-depth earthquakes (up to M similar to 8.0). A larger number of previously published Fault Plane Solutions (FPS), as well as additional FPS computed in the framework of this study, provide the basis for the detailed study of the Southern Aegean active stress field. The active stress field is examined using three well-established algorithms, as well as an adapted method proposed in this study, based on the statistical processing of solutions provided by the Gephart and Forsyth (1984) method. The results obtained from all methods show a systematic consistency, with the Gephart and Forsyth method exhibiting the largest discrepancy, in comparison to other approaches. The determined active stress field reveals several domains with similar seismotectonic characteristics. Along the Southern Aegean (Hellenic) volcanic arc, the roughly North-South extension field shows an excellent correlation with the local arc geometry (arc-normal extension). The outer arc is characterized by compression, as a result of the active subduction, with an almost constant NE-SW direction. Between these two regions, a narrow zone with approximately East-West extension develops along the whole Hellenic Arc with subtle spatial differences, while in the eastern Hellenic Arc a well-developed strike-slip faulting pattern is recognized along the broader area of the Pliny and Strabo trenches. Finally, all intermediate-depth events show the same transpressional pattern, with a characteristic down-dip extension along the subduction direction and an arc-parallel compression, which follows the local arc orientation.

机译：我们从故障平面解决方案数据检查了南极盟海面俯冲区域的主动应力领域，专注于由不同应力反转方法的应用产生的可变性。研究区的特点是高地震性水平，并且通过大的破坏性浅层和中间地震反复击中（高达M类似于8.0）。更大数量的先前公布的故障平面解决方案（FPS）以及在本研究框架中计算的额外FPS，为南方爱琴海有源应力场进行详细研究提供了基础。使用三种良好的算法检查有源应力场，以及本研究中提出的适应方法，基于Gephart和Forsyth（1984）方法提供的解决方案的统计处理。与其他方法相比，从所有方法获得的结果显示出系统的一致性，具有呈现最大差异的Gephart和Forsyth方法。所确定的主动应力场揭示了具有类似地震型特性的若干结构域。沿着南部爱琴海（希腊语）火山电弧，大致南北扩展领域与局部电弧几何（弧形正常扩展）显示出优异的相关性。外弧的特征在于，由于有源俯冲的结果，具有几乎恒定的NE-SW方向。在这两个地区之间，一个狭窄的区域，大约是东西延伸的沿着整个希腊电弧，具有微妙的空间差异，而在东部地狱般的弧度中，沿着普雷尼的更广泛的区域识别出良好开发的防滑断线图案Strabo战壕。最后，所有中间深度事件都示出了相同的横向图案，沿俯径方向具有特征下倾斜延伸和沿局部电弧取向的电弧平行压缩。

Active stress field of the Southern Aegean Sea subduction area from fault-plane solutions on the basis of different stress inversion approaches

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