The structure of the Alboran Sea: an interpretation from seismological andgeological data

Almost all the earthquakes included in the catalog for the Iberian-Maghrebi an area up to 2000 have been used in order to know the structure of the Alb oran Sea area after the verification of the aleatory nature of the errors i n their spatial localization. A new focal mechanisms catalog has also been used as well as many of the available geological data. During the Mesozoic and till the Oligocene, the Betic-Rif Internal Zone was situated further E, but with the opening of the Algero-Provencal basin in the early Miocene, the Betic-Rif Internal Zone moved to the W. Contemporary , the Alboran Sea was created as the western prolongation of the Algero-Pro vencal basin. The Betic-Rif Internal Zone overthrused part of the Iberian a nd African plates, producing the partial sinking of both plates and being r esponsible of the intermediate seismicity existing in the western sector of the Alboran S ea. The intermediate earthquakes in the Atlas towards the NE and WSW are no t related to lithospheric sinking but to significant deep faults limiting a subplate in NW Africa. In the Atlantic, the intermediate earthquakes betwe en the Gorringe sector and Gibraltar are produced in the contact between th e Iberian and African plates and by the important faults crossing it. The existence of four very deep earthquakes is related to the previous sink ing of the lithosphere originally associated to the domain in which the Bet ic-Rif Internal Zone was situated. (C) 2001 Elsevier Science B.V. All right s reserved.