Source model for the Mw 6.1, 31 March 2006, Chalan‐Chulan Earthquake (Iran) from InSAR

We use InSAR to measure deformation and kinematics of the Mw = 4.9 Borujerd (2005/05/03) and Mw = 6.1 Chalan-Chulan (2006/03/31) earthquakes that occurred in the Zagros fold-and-thrust belt. The focal mechanism of the 2006 event is consistent with right lateral strike-slip motion and the event ruptured the Dorud-Borujerd segment of the Main Recent Fault. An Envisat interferogram spanning the 2006 event shows peak ground deformation of 9 cm in the satellite line-of-sight along a 10 km long fault portion. The interferogram spanning the 2005 earthquake is rather related to atmospheric artefact than to ground deformation. Dislocation models of the 2006 Chalan-Chulan event indicate dextral slip amounting to a maximum of 90 cm at a depth of 4 km. The predicted vertical displacements are in good agreement with differential levelling data. The 2006 event filled only a small part of the seismic gap located between large M = 7 events that occurred in 1909 and 1957.

[1]  P. Segall,et al.  Comparison of various inversion techniques as applied to the determination of a geophysical deformation model for the 1983 Borah Peak earthquake , 1992, Bulletin of the Seismological Society of America.

[2]  C. J. Talbot,et al.  A new tectonic scenario for the Sanandaj–Sirjan Zone (Iran) , 2006 .

[3]  M. Sambridge.  Geophysical inversion with a neighbourhood algorithm—II. Appraising the ensemble , 1999 .

[4]  M. Berberian.  Master “blind” thrust faults hidden under the Zagros folds: active basement tectonics and surface morphotectonics , 1995 .

[5]  B. Meyer,et al.  Strike‐slip kinematics in Central and Eastern Iran: Estimating fault slip‐rates averaged over the Holocene , 2007 .

[6]  E. Engdahl,et al.  Relocation and assessment of seismicity in the Iran region , 2006 .

[7]  K. Feigl,et al.  Radar interferometry and its application to changes in the Earth's surface , 1998 .

[8]  Khaled Hessami,et al.  Active deformation within the Zagros Mountains deduced from GPS measurements , 2006, Journal of the Geological Society.

[9]  Howard A. Zebker,et al.  Decorrelation in interferometric radar echoes , 1992, IEEE Trans. Geosci. Remote. Sens..

[10]  N. Ambraseys,et al.  A history of Persian earthquakes , 1982 .

[11]  Demitris Paradissis,et al.  GPS constraints on continental deformation in the Africa‐Arabia‐Eurasia continental collision zone and implications for the dynamics of plate interactions , 2005 .

[12]  J. Jackson,et al.  A reappraisal of earthquake focal mechanisms and active shortening in the Zagros mountains of Iran , 2004 .

[13]  Pierre Briole,et al.  The source motion of 2003 Bam (Iran) earthquake constrained by satellite and ground‐based geodetic data , 2007 .

[14]  J. Tchalenko,et al.  Seismicity and structure of the Zagros (Iran): the Main Recent Fault between 33 and 35° N , 1974, Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences.

[15]  L. Jolivet,et al.  Transient, synobduction exhumation of Zagros blueschists inferred from P‐T, deformation, time, and kinematic constraints: Implications for Neotethyan wedge dynamics , 2006 .

[16]  P. Rosen,et al.  SYNTHETIC APERTURE RADAR INTERFEROMETRY TO MEASURE EARTH'S SURFACE TOPOGRAPHY AND ITS DEFORMATION , 2000 .

[17]  E. Shabanian,et al.  Late Cenozoic partitioning of oblique plate convergence in the Zagros fold‐and‐thrust belt (Iran) , 2006 .

[18]  J. Jackson,et al.  Offset on the Main Recent Fault of NW Iran and implications for the late Cenozoic tectonics of the Arabia-Eurasia collision zone , 2001 .

[19]  Y. Okada.  Surface deformation due to shear and tensile faults in a half-space , 1985 .

[20]  L. Jolivet,et al.  Convergence history across Zagros (Iran): constraints from collisional and earlier deformation , 2005 .

[21]  H. W. Wellman.  Active wrench faults of Iran, Afghanistan and Pakistan , 1966 .

[22]  N. McQuarrie,et al.  Crustal scale geometry of the Zagros fold–thrust belt, Iran , 2004 .

[23]  K. Priestley,et al.  A re‐assessment of focal depth distributions in southern Iran, the Tien Shan and northern India: do earthquakes really occur in the continental mantle? , 2000 .

[24]  Frederic Masson,et al.  Present‐day crustal deformation and plate kinematics in the Middle East constrained by GPS measurements in Iran and northern Oman , 2004 .

[25]  Howard A. Zebker,et al.  Phase unwrapping for large SAR interferograms: statistical segmentation and generalized network models , 2002, IEEE Trans. Geosci. Remote. Sens..

[26]  Rowena B. Lohman,et al.  Locations of selected small earthquakes in the Zagros mountains , 2005 .

[27]  David A. Seal,et al.  The Shuttle Radar Topography Mission , 2007 .

[28]  M. Sambridge.  Geophysical inversion with a neighbourhood algorithm—I. Searching a parameter space , 1999 .

[29]  O. Lacombe,et al.  Evidence of Quaternary activity along the Deshir Fault : implication for the Tertiary tectonics of Central Iran , 2006 .