pure and applied geophysics

, Volume 161, Issue 11–12, pp 2125–2137 | Cite as

Guided Waves from Sources Outside Faults: An Indication for Shallow Fault Zone Structure?

  • Miko Fohrmann
  • Heiner Igel
  • Gunnar Jahnke
  • Yehuda Ben-Zion
Article

Abstract

— 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.

Key words

Wave propagation fault zones trapped waves seismic hazard 

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Copyright information

© Birkhäuser Verlag, Basel, 2004

Authors and Affiliations

  • Miko Fohrmann
    • 1
    • 3
  • Heiner Igel
    • 1
  • Gunnar Jahnke
    • 1
    • 4
  • Yehuda Ben-Zion
    • 2
  1. 1.Department Earth and Environmental SciencesLudwig-Maximilians-UniversityMunichGermany
  2. 2.Department of Earth SciencesUniversity of Southern CaliforniaLos AngelesU.S.A
  3. 3.Geology DepartmentUniversity of OtagoDunedinNew Zealand
  4. 4.Bundesanstalt fürGeowissenschaften und RohstoffeHannover

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