Source Parameters of Weak Crustal Earthquakes of the Vrancea Region from Short-period Waveform Inversion
Source Parameters of Weak Crustal Earthquakes of the Vrancea Region from Short-period Waveform Inversion
复制标题
短周期波形反演弗朗恰地区地壳弱震震源参数
DOI：
10.1007/s00024-004-2618-y
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发表时间：
2005
影响因子：
2
通讯作者：
G. Panza
中科院分区：
文献类型：
--
作者：
L. Ardeleanu;M. Radulian;J. Šílený;G. Panza
用地震矩张量（MT）反演了罗马尼亚Vrancea地震区9次低震级浅源地震的高频记录。提出了一种方法，当地壳结构信息不足时，如何至少获得大地电磁测深的粗略估计。在这里，简单的1-D分层模型中使用的绿色的功能合成，尽管该区域的结构无疑是非常复杂的。不同的1-D模型用于不同的源站路径，以近似横向变化。然而，位于穿过与1-D模型基本上不同的结构的射线路径上的站的记录可能会使检索到的MT基本上偏置。因此，我们没有集体处理所有记录，而是单独处理站点的子集。我们检查的MT从这些个人的“引导”的解决方案产生的一致性，并拒绝那些差异很大，假设这是由于过度简化的正演建模。此后，由一致子集产生的平均力矩张量被接受。此外，分布的T，N和P轴的矩张量用于平均提供了一个粗略的估计其reliability. After这个简单的程序，我们发现了七个可接受的约束解决方案中处理的九个事件。将它们的P轴与本区应力的总体趋势进行了比较，其中3个与本区应力的总体趋势相符，其余的应归因于本区活动的复杂应力场。
High-frequency records of nine low magnitude shallow earthquakes of the Vrancea (Romania) seismic region are inverted for the seismic moment tensor (MT). An approach is suggested regarding how to obtain at least a rough estimate of the MT when the information on the structure of the crust is poor. Here simple 1-D layered models are used in the Green’s function synthesis despite the fact that the structure of the region is undoubtedly very complex. Different 1-D models were used for different source-station paths to approximate lateral variations. Record of a station located on a ray path which crosses a structure differing substantially from a 1-D model may however bias the retrieved MT essentially. Therefore, we did not collectively process all records, but subsets of stations separately. We check the consistency of the MTs resulting from these individual “bootstrap” solutions, and reject those which differ substantially, assuming that this is due to the oversimplification of the forward modeling. Thereafter, the averaged moment tensor yielded by the consistent subsets is accepted. Moreover, the distribution of the T, N and P axes from the moment tensors used for averaging provides a rough estimate of their reliability.Following this simplistic procedure, we found seven acceptably constrained solutions among nine events processed. Their P axes are compared with the general trend of the stress in the area: three comply with it, the others should be attributed to the complex stress field active in the region.