Nailing down the slip rate of the Altyn Tagh fault

Abstract

[1] Previous estimates of the geodetic and geologic slip rates of the 1500 km long Altyn Tagh fault bordering the northern edge of the Tibetan plateau vary by a factor of five. Proposed reasons for these discrepancies include poor GPS geometry, interpretative errors in terrace morphology, and changes in fault slip rate over time. Here we present results from a new dense GPS array orthogonal to the fault at~86.2°E that indicates a velocity of 9.0 À3.2 / +4.4 mm/yr, in close agreement with geomorphologic estimates at the same location. Our estimated geodetic slip rate is consistent with recent geological slip rates based on terrace offsets. The resulting mean combined geological and geodetic slip rate (9.0 ± 4.0 mm/yr) is remarkably uniform for the central 800 km of the Altyn Tagh fault, significantly lower than early kinematic estimates and consistent with deformation elsewhere in Tibet and central Asia.

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

“…It is also consistent with InSAR results of 11˘5 mm/year estimated from ERS data [16]. Similar to other geodetic measurements [15][16][17]68], we also identified the asymmetric deformation pattern between the two sides of the fault. The possible mechanisms to explain this interseismic velocity asymmetry maybe a variation of the elastic crustal thickness from rheological contrast on two sides of the ATF [68] or variation in fault dip angle.…”

“…The locking depth was not as well constrained as the other geodetic inversion results [14]. We note that the slip rate is in good agreement with GPS measurements of 9˘4 mm/year [17] almost 1˝east of our study area. It is also consistent with InSAR results of 11˘5 mm/year estimated from ERS data [16].…”

“…2016, 8,233 3 of 18 supporting continuum deformation. In contrast, He et al [17] tried to determine the slip rate using a GPS profile, and their conclusion was 9.0˘4.0 mm/year, consistent with block-like deformation. At a millennial time scale, the geological slip rate is given as 27˘7 mm/year from detailed measurements of riser offsets of different geomorphic terraces using radiocarbon and cosmic ray exposure dating of the offset terraces [18].…”

“…Elliott et al [16] investigated the same location as this study using ERS data and the stacking method and concluded that the slip rate was 11 ± 5 mm/year, supporting continuum deformation. In contrast, He et al [17] tried to determine the . The top left figure shows the whole tectonic background of the ATF, the low right figure is the zoom-in of the blue rectangular in it and shows the velocity map.…”

Present‐day crustal thinning in the southern and northern Tibetan Plateau revealed by GPS measurements

“…The data set of He et al [2013] contains 16 campaign-mode sites located in a localized dense network across central segment of Altyn Tagh Fault from the Tarim Basin to northern Tibet and measured twice in the period of 2009-2011. In addition, we show published velocities for surrounding regions (Figure 1): from the Nepal Himalaya [e.g., Banerjee et al, 2008;Bettinelli et al, 2006;Bilham et al, 1997;Feldl and Bilham, 2006], northwest Himalaya [Banerjee and Bürgmann, 2002], Pamir-Hindu Kush [Ischuk et al, 2013;Mohadjer et al, 2010], Kashmir and Ladakh Himalaya [e.g., Jade et al, 2004;Schiffman et al, 2013], eastern Himalaya, Naga Hills, and Shillong Plateau [Devachandra et al, 2014;Vernant et al, 2014].…”