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1 EOSTInstitut de Physique du
Globe
5, rue René Descartes
67084 Strasbourg Cedex,
France
ziyadin.cakir{at}eost.u-strasbg.fr
(Z.C.,
M.M., S.B.)
2 Eurasian Institute of Earth Sciences
ITU
Istanbul, Turkey
(A.M.A.)
3 Laboratoire de
Geophysique
CNRST
Rabat, Morocco
(N.J.)
4 des Sciences de la
Terre
Universite Mohammed V
Morocco
(L.A.-B.)
We study the surface deformation associated with the 24 February 2004 Al Hoceima earthquake (Mw 6.4) that recently affected the Rif Mountains of Morocco. The coseismic displacement field is mapped using synthetic aperture radar interferometry (InSAR) with the Envisat (ESA) satellite data acquired in the ascending and descending modes. Our analysis and modeling of InSAR data suggest that the earthquake is associated with a northwestsoutheast-trending right-lateral, apparently blind strike-slip fault with a seismic moment reaching 6.8 x 1018 N m. This result is in contrast with the north-northeastsouth-southwest left-lateral fault mechanism inferred from the modeling of seismic waves. Thrust-and-fold structures of the Rif Mountains developed during the Tertiary period, but the recent significant seismic events and late-Quaternary deformation indicate eastwest extension accommodated by northsouth-trending normal and northwestsoutheast- and northeast southwest-trending conjugate strike-slip faults. The active deformation illustrates the fragmentation of the Rif Mountain range due to the AfricaIberia collision and west- southwestward escape tectonics.
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