Journal of Geodynamics 44 (2007) 200–212 Coseismic deformation and slip distribution of the 1997 M w 7.5 Manyi, Tibet, earthquake from InSAR measurements Hua Wang a,∗,1 , Caijun Xu a , Linlin Ge b a School of Geodesy and Geomatics, Wuhan University, 129 Luoyu Road, Wuhan 430079, China b School of Surveying Spatial Information Systems, The University of New South Wales, Sydney, NSW 2052, Australia Received 28 September 2006; received in revised form 12 March 2007; accepted 13 March 2007 Abstract We use interferometric synthetic aperture radar (InSAR) observations to investigate the coseismic deformation and slip distribution of the 1997 M w 7.5 Manyi earthquake, a left-lateral strike-slip earthquake occurred on the west portion of the Kunlun fault in the northern Tibet, China. The fault trace is constrained by the combination of interferometric coherence image and azimuth offset image. The total length of the identified fault is about 170 km. We estimate the source parameters using a seven-segment fault model in a homogeneous elastic half-space. We first use a uniform slip model to estimate the slip, width, dip and rake for each segment, resulting in a maximum slip of 5.5 m with a depth of 11 km on the fourth segment. The average dip of the uniform slip model is about 93 ◦ northward and the average rake is about -2 ◦ . We then use a distributed slip model to estimate the pure strike-slip and oblique slip distribution, respectively. In the distributed slip model, the fault plane is discretized into 225 patches, each of them 4 km × 4 km. We fix the optimal geometric parameters and solve for the slip distribution using a bounded variable least-squares (BVLS) method. We find a geodetic moment of 1.91 × 10 20 Nm (M w 7.5), of which almost 68% released in the uppermost 8 km and 82% in the uppermost 12km. For all the models used in this study, the synthetic profiles along strike show asymmetric displacements on the opposite sides of the fault, which are in agreement with the observations. This suggests that a linear elastic model with variable and non-vertical dips is also reasonable for the mechanism of the Manyi earthquake. © 2007 Elsevier Ltd. All rights reserved. Keywords: Manyi earthquake; InSAR; Uniform slip; Distributed slip; Linear elastic; Asymmetry 1. Introduction The Kunlun fault is one of the largest strike-slip faults in the Tibetan plateau. It locates at the south of the Altyn Tagh fault and extends almost 1200km from the northeast Tibet, separating the Qaidam Basin to the northeast from the plateau (Fig. 1). Using satellite imagery, Tapponnier and Molnar (1977) found a number of secondary strike-slip faults, including the Manyi fault, at the west end of the Kunlun fault. The latest earthquake associated with these faults is the 4 July 1973 M s 7.4 event, which might reactivate these secondary faults (Tapponnier and Molnar, 1977). Global Positioning System (GPS) observations and geological investigations show a left-lateral strike-slip rate of 10–14 mm/year on the Kunlun fault (e.g., Wang et al., 2001; Zhang et al., 2004; Van der Woerd et al., 2000). ∗ Corresponding author. Fax: +86 27 68778890. E-mail address: ehwang@163.com (H. Wang). 1 Present address: Guangdong University of Technology, China. 0264-3707/$ – see front matter © 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.jog.2007.03.003