Journal of Seismology

, Volume 17, Issue 2, pp 207–222 | Cite as

The Constantine (Algeria) seismic sequence of 27 October 1985: a new rupture model from aftershock relocation, focal mechanisms, and stress tensors

  • F. OusadouEmail author
  • L. Dorbath
  • C. Dorbath
  • M. A. Bounif
  • H. Benhallou
Review Article


The October 27, 1985 Constantine earthquake of magnitude MS 5.9 (NEIC) although moderate is the strongest earthquake recorded in the eastern Tellian Atlas (northeast Algeria) since the beginning of instrumental seismology. The main shock locations given by different institutions are scattered and up to 10 km away northwest from the NE–SW 30 km long elongated aftershocks cloud localized by a dedicated temporary portable network. The focal mechanism indicates left-lateral strike-slip on an almost vertical fault with a small reverse component on the northwest dipping plane. This paper presents relocations of the main shock and aftershocks using TomoDD. One hundred thirty-eight individual focal mechanisms have been built allowing the determination of the stress tensor at different scales. A rupture model has been suggested, which explains the different observations of aftershock distribution and stress tensor rotation.


Aftershocks Tellian Atlas Focal mechanisms Stress tensors Coulomb failure stress 



We gratefully acknowledge the two anonymous reviewers and the editor for their fruitful comments that substantially improved this manuscript. We express our gratitude to Mustapha Meghraoui for the discussion about the surface ruptures of the studied earthquake, Seid Bourouis for his help in the preparation of some figures, Rémi Dretzen from the RéNass for his help to relocate the main shock using the RéNass procedure, and Jérome Van der Woerd for his assistance in the preparation the manuscript. We would like to remember one of our co-author, Prof. Hadj Benhalou, who passed away recently on October 16, 2011 after a long illness. This study has been supported by the CRAAG and the EOST, University of Strasbourg, and the TASSILI CMEP project (11 MDU 847).


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Copyright information

© Springer Science+Business Media B.V. 2012

Authors and Affiliations

  • F. Ousadou
    • 1
    Email author
  • L. Dorbath
    • 2
  • C. Dorbath
    • 2
  • M. A. Bounif
    • 3
  • H. Benhallou
    • 3
  1. 1.Centre de Recherche en Astronomie Astrophysique et Géophysique (CRAAG)AlgiersAlgeria
  2. 2.Université de Strasbourg. Ecole et Observatoire des Sciences de la Terre (EOST)Strasbourg CedexFrance
  3. 3.Université de Sciences et de Technologie Houari Boumediene (USTHB/FSTGAT)AlgiersAlgeria

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