مرکز منطقه ای اطلاع رساني علوم و فناوري -

چكيده لاتين :

Co-seismi c surf ace def ormation measurements in the vic inity of a ruptured fault provide cons traints on detailed fault geometry and slip distribution at depth . Together with seismologi cal data , they give unique insights on the mechanical behaviour of a seismicfa ult. Three different satellite andground geodetic measurements of Bam earthquake (Mw 6.6, December 26, 2003) induced surfa ce deformation are present ed. Envisat ASAR int erf erometry provides precise and dense inf ormation. However, due to this strike-slip fault orientation, sub-pixel correlation technique appl ied to Spot-5 images makes more explicit the horizontal component ofsurf ace def ormation. We comp lete these oblique and horizontal estimations of def ormation with a levelling profile along the main road crossing the rupture from west to east. This geodetic data allows us to propose a dislocation model at depth . The slip vector, on a quasi-vertical fault, slightly dipping towards east, has a strike-slip component as high as 2m, while the dip-slip component appears to be small. We sugges t that ruptu re may have been initiated at depth on the Bam fault and propagated towards surface along this new f ault branch . In addition to co-seismic deformation, InSAR analysis and levelling data rev eal the presence of a high-rate subsiding zone south-east ofBam city. The ph enom enon is likely due to heavy water withdrawal f or cultivation purpose or water supply to the Bam and Baravat inhabitants. Ultimately, we present a work in progress involving GPS and InSAR which aims to map post-seismic deformation in the vicinity of Bam. However, technical problems in GPS camp aigns and atmospheric artifacts in InSAR acquisitions did not enable us to show any e vidence of su ch a deformation so far.