Guided Waves from Sources Outside Faults: An Indication for Shallow Fault Zone Structure?
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- 作者：Miko Fohrmann ; Heiner Igel ; Gunnar Jahnke and Yehuda Ben-Zion
- 关键词：Wave propagation ; fault zones ; trapped waves ; seismic hazard
- 刊名：Pure and Applied Geophysics
- 出版时间：December 2004
- 出版年：2004
- 期刊代码：123_0033-4553
- 类别：ear
- 卷：161
- 期：11-12
- 页码：2125-2137
- 数据来源：sp
摘要
— Using 3-D numerical modeling of seismic wave propagation we investigate the possibility of generating fault zone (FZ) trapped wave energy from sources well outside a fault. The FZ is represented by a O(200 m) wide vertical low velocity layer in a half space. We find that FZ trapped waves can be excited from sources well outside the fault if (1) the low-velocity structure extemds only to shallow depth and the source is located at greater depth or (2) the structure of the low-velocity zone is such that only the shallow part of the FZ traps energy. FZ trapped waves are not excited from sources well outside a FZ continuous with depth. The results support, in conjunction with recent observational evidence, a model for natural faults with shallow trapping structures rather than ones that span the entire seismogenic zone. This may have implications for fault mechanics as well as for aspects of shaking hazard near faults.