Lithospheric Structure and Seismotectonics of the Gibraltar Arc and Alboran Sea of Northern Morocco and Southern Spain

Cornell University,  Ithaca, USA

Instituto Andaluz Geofisica , Granada, Spain

Instituto Geografico Nacional, Madrid, Spain

Centre National de Coordination et de Planification de la Recherche Scientifique et Technique, Rabat, Morocco

Funded by the National Science Foundation
To view the results from this work please go here.

The diffuse boundary between Africa and Iberia is a type-example of the complex deformation associated with convergence of continental plates.

This boundary includes the Moroccan Rif and Spanish Betic interplate mountain belts, which together constitute the Gibraltar Arc, and the Alboran Sea.  Deformation continues today, evidenced by both shallow and intermediate depth seismicity. 

A number of competing models have been suggested to explain the apparent coeval development of these striking arcuate fold and thrust mountain belts and the neighboring Alboran basin since the early Miocene. Possible models range from trapped microplates to subduction or delamination.

Such models can be discriminated by a detailed investigation of the lithospheric structure and the seismotectonics of the area. The proposed evolutionary models make predictions of the present spatial distribution and characteristics of seismicity, seismic wave velocities, and attenuation.

We are mapping these attributes in three dimensions in order to test these predictions, and develop a constrained geodynamic model for the region. Specifically, we are:

• Determining accurate earthquake locations and focal mechanisms (at both shallow and intermediate depths).

• Using the two station method to measure seismic wave velocities and study Sn attenuation to map upper mantle structures and the lateral extent of previously suggested asthenosphere-crust contacts, and using digital waveforms to estimate Q.

• Performing a high resolution tomographic inversion for the velocity and attenuation structure.
   

This research project involves close collaborative work with both Moroccan and, for the first time, Spanish research institutions. Our main contacts and host institutions are the National Research Center in Rabat, Morocco, Instituto Geografico Nacional in Madrid, Spain, and Instituto Andaluz Geofisica in Granada, Spain, all which administer and operate regional seismological networks. The combined networks allow access to digital waveforms from 49 stations arrayed on both sides of the Alboran Sea. This concentration of seismological data offers an exciting opportunity for a very detailed and precise study of the geodynamic processes shaping this important, yet still enigmatic region.

Modified from NSF proposal project summary

To view the results from this work please go here.

If you have questions about these activities please contact Muawia Barazangi.