Abstract
The Altyn Tagh Fault (ATF) is one of the major left-lateral strike-slip faults in the northeastern area of the Tibetan Plateau. In this study, the interseismic deformation across the ATF at 85°E was measured using 216 interferograms from 33 ENVISAT advanced synthetic aperture radar images on a descending track acquired from 2003 to 2010, and 66 interferograms from 15 advanced synthetic aperture radar images on an ascending track acquired from 2005 to 2010. To retrieve the pattern of interseismic strain accumulation, a global atmospheric model (ERA-Interim) provided by the European Center for Medium Range Weather Forecast and a global network orbital correction approach were applied to remove atmospheric effects and the long-wavelength orbital errors in the interferograms. Then, the interferometric synthetic aperture radar (InSAR) time series with atmospheric estimation model was used to obtain a deformation rate map for the ATF. Based on the InSAR velocity map, the regional strain rates field was calculated for the first time using the multi-scale wavelet method. The strain accumulation is strongly focused on the ATF with the maximum strain rate of 12.4 × 10−8/year. We also show that high-resolution 2-D strain rates field can be calculated from InSAR alone, even without GPS data. Using a simple half-space elastic screw dislocation model, the slip-rate and locking depth were estimated with both ascending and descending surface velocity measurements. The joint inversion results are consistent with a left-lateral slip rate of 8.0 ± 0.7 mm/year on the ATF and a locking depth of 14.5 ± 3 km, which is in agreement with previous results from GPS surveys and ERS InSAR results. Our results support the dynamic models of Asian deformation requiring low fault slip rate.
Highlights
The ongoing active continental collision between the Indian and Eurasian plates has created the massive topography of the Tibetan Plateau over the last 50 million years
Using a multi-scale wavelet method, we calculated the strain rate fields of the Altyn Tagh Fault (ATF) region and determined that the strain was mainly localized along the fault, which is generally consistent with previous studies
We show that high-resolution 2-D strain rate fields can be determined from interferometric synthetic aperture radar (InSAR) data alone, especially in regions with spatially sparse GPS data
Summary
The ongoing active continental collision between the Indian and Eurasian plates has created the massive topography of the Tibetan Plateau over the last 50 million years. The active Altyn Tagh Fault (ATF) is a distinctive feature of Tibetan geography, inscribing a fairly linear trace over 1500 km across northern Tibet (Figure 1), separating the high plateau in the south from the low Tarim Basin in the north. The Tibetan Plateau south of the ATF has an average elevation of ~4000 m, whereas the northern Tarim Basin has an average elevation of only ~1000 m. It is generally accepted that the ATF is divided into three segments, the west, middle, and east, between 84 ̋ E and 94 ̋ E [5]. It is a major tectonic element in Remote Sens. It is a major tectonic element in Remote Sens. 2016, 8, 233; doi:10.3390/rs8030233 www.mdpi.com/journal/remotesensing
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