Journal of Seismology

, Volume 20, Issue 4, pp 1075–1088 | Cite as

Source mechanism studies of earthquakes in the Ibero-Maghrebian region and their tectonic implications

  • E. Buforn
  • A. Udías
  • C. Pro
Original Article


Seismicity of the Ibero-Maghrebian region includes the occurrence of shallow, intermediate depth, and very deep earthquakes. This is a very rare occurrence for a region not associated to an active subduction zone. Detailed studies of the source mechanism of these three types of earthquakes have been made possible through the collaboration with Prof. Madariaga. They give important information about the complex tectonic of the region. Shallow earthquakes at the west and east ends of the region have predominant reverse faulting with NW-SE trending horizontal pressure axes. The center part is the most tectonically complex. At the Strait of Gibraltar, there is a change on focal mechanisms from reverse faulting to strike-slip motion in northern Morocco, conserving the horizontal compression on NW-SE direction. In the Alboran Sea, mechanisms are of normal faulting with E-W trending horizontal tension axes, and in south Spain, mechanisms are of mixed solutions. The intermediate depth earthquakes (40–130 km) are located at both sides of the Strait of Gibraltar, at the western part distributed in E-W direction. The most important concentration, however, is located at the east of Gibraltar in a N-S trending thin vertical body and has different mechanisms. The very deep earthquakes (650 km) are concentrated at a small volume, and their mechanism corresponds to N-S vertical planes or horizontal ones. A tectonic model for the region is presented to explain the shallow, intermediate, and deep earthquakes.


Ibero-Maghrebian region Source mechanism Seismic slip distribution Tectonic model 



The authors want to thanks Dr. S. Cesca (GFZ, Potsdam) who provided Fig. 7, Prof. M. Bezzeghoud (University of Evora, Portugal), Dr. J. M. Martínez Solares (IGN, Madrid) for the helpful discussion, and the referees for their comments which have improved the quality of manuscript. This work has been partially supported by MINECO, project CGL2013-45724-C3-R-1, by the INNOCAMPUS project (Ministerio de Economía y Competitividad, Orden CIN/1934/2010) and by Programa de Financiación UCM-Santander Ayuda a Grupos de InvestigaciónValidados GR3/14).


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Copyright information

© Springer Science+Business Media Dordrecht 2016

Authors and Affiliations

  1. 1.Departamento de Geofísica y Meteorología/Universidad ComplutenseMadridSpain
  2. 2.IGEO, UCM-CSICMadridSpain
  3. 3.Departamento de Física/Universidad de ExtremaduraMéridaSpain

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