pure and applied geophysics

, Volume 136, Issue 2–3, pp 281–296 | Cite as

Elastic finite difference modelling of lower crustal reflections

  • J. F. Andrier
Article
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Abstract

It is a common feature to observe on deep reflection profiles, short (less than the Fresnel area diameter) and strongly discontinuous lower crustal reflections. Such wave patterns can be attributed to variations in the crustal properties on the scale of a few wavelengths. In order to explain these characteristics, we have computed finite-difference synthetic seismograms for various types of deep heterogeneities. Focusing, defocusing and interference effects were especially studied. The results can only be interpreted in a qualitative manner because our models exhibit departures from the real cases (lower frequency content, and only two-dimensional structures). It is found that simple undulations of the deep interfaces can hardly produce the discontinuous pattern observed, but high velocity intrusions generate complex interferences matching the reflection character of real data. Furthermore, the reflection patterns strongly depend both on length and shape of the inclusions.

Key words

Heterogeneities lower crust modelling reflection seismic 
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Copyright information

© Birkhäuser Verlag 1991

Authors and Affiliations

  • J. F. Andrier
    • 1
  1. 1.Laboratoire de Geophysique MarineUniversité de Bretagne OccidentaleBrest cedexFrance

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