Combination of Precise Leveling and InSAR Data to Constrain Source Parameters of the Mw = 6.5, 26 December 2003 Bam Earthquake

Motagh, Mahdi; Klotz, J.; Tavakoli, Farokh; Djamour, Y.; Arabi, Siavash; Wetzel, Hans‐Ulrich; Zschau, Jochen

doi:10.1007/s00024-005-0005-y

Cited by 40 publications

(31 citation statements)

References 25 publications

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“…Seismological and geodetic source models proposed that slip in the earthquake was concentrated between 2-8 km depth, with a maximum fault slip of 2.7 m (Fialko et al 2005;Funning et al 2005;Stramondo et al 2005;Motagh et al 2006;Peyret et al 2007). However, the pattern of aftershocks extended well beneath the co-seismic slip patch, to nearly 20 km depth (Nakamura et al 2005;Tatar et al 2005), suggesting the bottom ∼10 km of the fault zone remained unruptured, yet is able to generate earthquakes.…”

Section: Introductionmentioning

confidence: 99%

Fault mechanics and post-seismic deformation at Bam, SE Iran

Wimpenny¹,

Copley²,

Ingleby

2017

Geophysical Journal International

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S U M M A R YThe extent to which aseismic deformation relaxes co-seismic stress changes on a fault zone is fundamental to assessing the future seismic hazard following any earthquake, and in understanding the mechanical behaviour of faults. Here we use models of stress-driven afterslip and viscoelastic relaxation, in conjunction with post-seismic InSAR measurements, to show that there has been minimal release of co-seismic stress changes through post-seismic deformation following the 2003 M w 6.6 Bam earthquake. Our analysis indicates the faults at Bam remain predominantly locked, suggesting that the co-plus interseismically accumulated elastic strain stored downdip of the 2003 rupture patch may be released in a future M w 6 earthquake. Our observations and models also provide an opportunity to probe the growth of topography at Bam. We find that, for our modelled afterslip distribution to be consistent with forming the sharp step in the local topography over repeated earthquake cycles, and also to be consistent with the geodetic observations, requires either (1) far-field tectonic loading equivalent to a 2-10 MPa deviatoric stress acting across the fault system, which suggests it supports stresses 60-100 times less than classical views of static fault strength, or (2) that the fault surface has some form of mechanical anisotropy, potentially related to corrugations on the fault plane, that controls the sense of slip.

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Section: Introductionmentioning

confidence: 99%

Fault mechanics and post-seismic deformation at Bam, SE Iran

Wimpenny¹,

Copley²,

Ingleby

2017

Geophysical Journal International

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“…Remote sensing measurements using techniques such as Interferometric Synthetic Aperture Radar (InSAR) are becoming increasingly important in such studies as they provide regional and spatially-continuous maps of deformation with great accuracy (< cm), without the need of performing much field work or expensive ground surveys [1][2][3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

StaMPS Improvement for Deformation Analysis in Mountainous Regions: Implications for the Damavand Volcano and Mosha Fault in Alborz

2015

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Interferometric Synthetic Aperture Radar (InSAR) capability to detect slow deformation over terrain areas is limited by temporal decorrelation, geometric decorrelation and atmospheric artefacts. Multitemporal InSAR methods such as Persistent Scatterer (PS-InSAR) and Small Baseline Subset (SBAS) have been developed to deal with various aspects of decorrelation and atmospheric problems affecting InSAR observations. Nevertheless, the applicability of both PS-InSAR and SBAS in mountainous regions is still challenging. Correct phase unwrapping in both methods is hampered due to geometric decorrelation in particular when using C-band SAR data for deformation analysis. In this paper, we build upon the SBAS method implemented in StaMPS software and improved the technique, here called ISBAS, to assess tectonic and volcanic deformation in the center of the Alborz Mountains in Iran using both Envisat and ALOS SAR data. We modify several aspects within the chain of the processing including: filtering prior to phase unwrapping, topographic correction within three-dimensional phase unwrapping, reducing the atmospheric noise with the help of additional GPS data, and removing the ramp caused by ionosphere turbulence and/or orbit errors to better estimate crustal deformation in this tectonically active region. Topographic correction is done within the three-dimensional unwrapping in order to improve the phase unwrapping process, which is in contrast to OPEN ACCESS Remote Sens. 2015, 7 8324 previous methods in which DEM error is estimated before/after phase unwrapping. Our experiments show that our improved SBAS approach is able to better characterize the tectonic and volcanic deformation in the center of the Alborz region than the classical SBAS.In particular, Damavand volcano shows an average uplift rate of about 3 mm/year in the year 2003-2010. The Mosha fault illustrates left-lateral motion that could be explained with a fault that is locked up to 17-18 km depths and slips with 2-4 mm/year below that depth.

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“…The earthquake signal south of the Bam city can clearly be seen. Figure 4A.1 shows displacements along the north-south oriented (Fialko et al, 2005;Motagh et al, 2006) earthquake causative fault that were previously unknown (Jonsson et al, 2004). Higher values in the urban, mountainous and vegetated areas are due mainly to temporal decorrelation and earthquake induced damages.…”

Section: A4 Resultsmentioning

confidence: 95%

“…The post-earthquake ASAR image was recorded 47 days after the earthquake. There was no evidence of any post-seismic displacement within that period (Fialko et al, 2005;Motagh et al, 2006;Peyret et al, 2007). It has been postulated that the earthquake causative fault had an extension towards the north, passing below the city Peyret et al, 2006).…”

Section: A2 Datasetmentioning

confidence: 92%

“…In the present study, horizontal coseismic displacements were determined using ENVISAT-ASAR pre-and post-earthquake SAR images from the descending orbit using pixel tracking. Note that there was no evidence of any post-seismic displacement after the Bam earthquake within the period of ASAR post-earthquake image (Fialko et al, 2005;Jackson et al, 2006;Motagh et al, 2006;Peyret et al, 2007).…”

Section: A1 Introductionmentioning

confidence: 99%

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Geostatistical and space geodetic methods on a 3D coseismic displacement field

Yaseen¹

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SummaryCoseismic displacements at the Earth's surface arise due to the release of energy by earthquakes. The energy, and hence the amount of displacement, depends mainly on the magnitude, depth and the movement mechanism of an earthquake. Coseismic displacements play a vital role in the characterization of geological faults and understanding of earthquake dynamics. This understanding is based in turn on the accurate measurement of coseismic displacements and creation of a continuous-field displacement map. The main objective of this research was to measure the coseismic displacements and to construct a 3D coseismic displacement field for an earthquake.Displacements are typically measured by comparing pre-and postearthquake radar images. In this study InSAR is used that measures phase (time) differences between pre-and post-earthquake SAR images resulting in displacements into line-of-sight (LOS) direction. The LOS is mainly sensitive in the vertical direction, moderately in the across flight direction and insensitive in the along flight direction. To measure the along-flight displacement component pixel tracking was used, providing azimuth offsets (AZO). Pixel tracking correlates the coregistered pre-and post-earthquake optical or SAR images. In this study pixel tracking was used for both SAR and optical data, whereas InSAR is used for SAR data only. Using the obtained displacement results, a 3D displacement field was generated from both descending and ascending image pairs bracketing the earthquake event.The study considered the 2003 Bam earthquake. The city is located on a geological fault that caused occurrence of the earthquake. From the measured displacements it appeared that the major part of the fault is located south of the city. It has a length of 13 km and the fault strike equals 170º, close to the along flight direction. The major vertical displacement occurred on east of the fault, showing a uplift in the south-eastern part of displacement map and subsidence in its north-eastern part. Horizontal displacements showed a relative movement along the fault in the along flight direction. The displacement was greater in horizontal direction than the LOS, revealing that the earthquake causative fault is a strike-slip fault.A displacement map commonly contains missing coseismic values due to lack of coherence between SAR images. In this study, missing displacement values were caused by non-coherence of pre-and post-earthquake SAR images for the area affected by the earthquake. These missing displacement values may be important for fault characterization, in particular if they occur along the earthquake-causative geological fault. Missing values were interpolated to evaluate the continuity of the earthquake causative fault underneath the city of Bam. i To assess the accuracy of the interpolated coseismic values, subsets of missing co-seismic values were selected and translated towards locations where displacement values exist. Here, missing values were generated artificially. These values were interpolate...

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Combination of Precise Leveling and InSAR Data to Constrain Source Parameters of the Mw = 6.5, 26 December 2003 Bam Earthquake

Cited by 40 publications

References 25 publications

Fault mechanics and post-seismic deformation at Bam, SE Iran

Fault mechanics and post-seismic deformation at Bam, SE Iran

StaMPS Improvement for Deformation Analysis in Mountainous Regions: Implications for the Damavand Volcano and Mosha Fault in Alborz

Geostatistical and space geodetic methods on a 3D coseismic displacement field

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