Broadscale interseismic deformation and fault slip rates in the central Tibetan Plateau observed using InSAR

Abstract

[1] Knowledge of the number, location, and interseismic slip rate of crustal faults is key to our understanding of the bulk mechanics of continental deformation. However, at present, the sparsity of geodetic velocity observations is a major limiting factor to improving our knowledge of the fault network. In this study, we combine long-swath interferometric synthetic aperture radar (InSAR) data to form an interseismic displacement rate map of over 1000 km length spanning the central Tibetan Plateau. Our dense geodetic observations indicate that strain varies smoothly in space without major concentration at previously mapped faults. Discrepancy between line-of-sight InSAR and GPS observations between 33 ı N-35 ı N could indicate 4 mm/yr of surface uplift in this region. Derived strain rates are less than 5 10 -8 yr -1 across the plateau. At the E-W left-lateral Kunlun fault, postseismic deformation following the 2001 Kokoxili earthquake results in an observed strain rate of 18˙4 10 -8 yr -1 across a 100 km wide zone. Following removal of a viscoelastic model, we estimate an interseismic slip rate of 12˙2 mm/yr for the Kunlun fault. In the central Tibetan conjugate fault zone, the NE-SW striking Amdo-Sewa and NW-SE striking Beng Co faults have right-lateral slip rates of 6˙1 mm/yr and 1-4˙1 mm/yr, respectively. Meanwhile, the NE-SW striking Dongqiao fault has a left-lateral slip rate of 1-2˙1 mm/yr. The low slip rates we estimate for these faults indicate that tectonic strain is more broadly distributed across the plateau interior, perhaps due to the lithosphere being weak and without the abrupt strength contrasts that exist at the plateau margins.Citation: Garthwaite, M. C., H. Wang, and T. J. Wright (2013), Broadscale interseismic deformation and fault slip rates in the central Tibetan Plateau observed using InSAR,

Interseismic Deformation of the Altyn Tagh Fault Determined by Interferometric Synthetic Aperture Radar (InSAR) Measurements

“…It is widely used to estimate the slip rates of major faults [16,21,22,27,28] since Massonnet et al successfully extracted the coseismic deformation of the 1992 Landers earthquake [20]. Wright et al [21] werethe first to use InSAR for studying the interseismic deformation.…”

“…Wright et al [21] werethe first to use InSAR for studying the interseismic deformation. InSAR has been proven to be a important tool in researching the seismic cycle deformation after many successful applications in coseismic [20], postseismic [29] and interseismic [16,21,22,27,28] deformation. Walters et al [22] improved Wright and coworkers' results [21] by using SAR data from two different look directions, in their paper, they stated that the uncertainties in slip rate and locking depth are reduced up to 60% which is a huge improvement.…”

Constraining crustal velocity fields with InSAR for Eastern Turkey: Limits to the block‐like behavior of Eastern Anatolia

“…This method is based on the methods developed by Biggs et al [2007], Elliott et al [2008], and Wang et al [2009] and to implement it we use the π-RATE (Poly-Interferogram Rate And Time-series Estimator) MATLAB-based software package . We correct orbital errors on an epoch-by-epoch basis by removing a six-parameter quadratic phase ramp from each interferogram, and in order to avoid the erroneous removal of long-wavelength deformation signals, we remove a GPS-derived a priori initial deformation model before orbital error estimation and then add back the subtracted model before rate map estimation [e.g., Wei et al, 2010;Garthwaite et al, 2013]. We assume that velocity is constant over the total time span of all our InSAR observations.…”

“…We estimate residual orbital errors on an epoch-by-epoch basis using a network approach and a quadratic orbital error correction, whereby a six-parameter quadratic phase ramp is used to correct each interferogram [e.g., Wei et al, 2010;Garthwaite et al, 2013]. In order to avoid the erroneous removal of long-wavelength deformation signals, we remove a GPS-derived a priori initial deformation model before orbital error estimation and then add back the subtracted model before rate map estimation [e.g., Wei et al, 2010;Garthwaite et al, 2013].…”

“…In order to avoid the erroneous removal of long-wavelength deformation signals, we remove a GPS-derived a priori initial deformation model before orbital error estimation and then add back the subtracted model before rate map estimation [e.g., Wei et al, 2010;Garthwaite et al, 2013]. This model contains predicted LOS velocities at each pixel, converted from horizontal GPS velocities in a fixed-Eurasia reference frame.…”