Investigation of Post-seismic and Inter-seismic Displacement Field Following 2003 Bam Earthquake in Iran Based on PS-InS
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RESEARCH ARTICLE
Investigation of Post-seismic and Inter-seismic Displacement Field Following 2003 Bam Earthquake in Iran Based on PS-InSAR Technique Samane Shokrzade1 • Behzad Voosoghi1 • Masoome Amighpey1 • Mostafa Rahmani1
Received: 10 October 2015 / Accepted: 30 May 2016 Ó Indian Society of Remote Sensing 2016
Abstract In this paper, Bam post-seismic deformations during 7 years after earthquake have been extracted using persistent scatterer interferometry technique. The results illustrate that the maximum amount of uplift and subsidence displacements along line of sight direction during 2004–2010 after the earthquake are 4.5 ± 0.5 and - 4.3 ± 0.5 cm, respectively. The results of displacement field indicate that an exponential function with the relaxation time of 2.5 years can be fitted to the corresponding process. The estimated inter-seismic slip value by the inversion of SAR line-of-sight data after relaxation time is 6.35 ± 0.05 mm. Mechanical time dependent processes in the post-seismic relaxation typically rely on models of poroelastic rebound, afterslip fault dilatancy recovery and viscoelastic relaxation to explain surface displacements field. The time series are inverted for the afterslip distribution on an extension of the co-seismic rupture. The estimated post-seismic slip value is 20.45 ± 0.38 cm. Most of the post-seismic displacement field can be explained in terms of fault slip. The results of post-seismic motion modeling indicate that the poroelastic rebound can be detected using the line-of-sight data and the effect of
& Samane Shokrzade [email protected] Behzad Voosoghi [email protected] Masoome Amighpey [email protected]; [email protected] Mostafa Rahmani [email protected] 1
Faculty of Geodesy and Geomatics Engineering, K. N. Toosi University of Technology (KNTU), Vali_asr St., Mirdamad Conjunction, Tehran, Iran
viscoelastic relaxation in post-seismic displacement is negligible. Keywords Postseismic Interseismic InSAR Persistent Scatterer Interferometry Poroelastic rebound Viscoelastic relaxation Afterslip
Introduction An earthquake with the magnitude of 6.6 on 26 MW both amplitude and phase rocked Bam, Iran on 26 December 2003. ENVISAT radar data indicates that the earthquake main shock didn’t occur on previously mapped Bam fault, but on an unknown blind strike slip fault extending *12 km southward from the center of the city (Talebian and Fielding 2004; Funning et al. 2005). The capability of interferometry synthetic aperture radar (InSAR) for precise deformation analysis has been shown in various case studies (Gabriel et al. 1989; Amighpey et al. 2014). To extract a source mechanism from earth surface observation, we measured the post-seismic displacement field of earthquake using InSAR. Persistent scatterer (PS) InSAR, technique addresses both the decorrelation and atmospheric problems of conventional small baseline approach. This technique is useful when we have temporal decorrelation and low deformation rate. Moreover this technique can reduce
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