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Abstract

In this study, we measure the interseismic deformation across the western Haiyuanfault. This fault is a major left-lateral fault at the north-eastern edge of the Tibetanplateau. Our aim is to better constrain its present mechanical behavior, at the originof two M ̃8 earthquakes in 1920 and 1927, and along which a seismic gap with highpotential seismic hazard has been identified. The gap is covered by ERS and Envisatdata along three adjacent tracks. Along the two easternmost tracks, a steep velocitygradient has been observed across the fault, consistent with a left-lateral slip at a rateof 6.3 ́s2 mm/yr below a small apparent locking depth (<2 km), which may be in-dicative of transient superficial creep or related to a weak fault zone (Cavalié et al.2008). The western track has not yet been studied as it covers a very high mountain-ous area, which introduces strong geometrical decorrelation. In this study, we focuson this track and propose a new InSAR adaptive range filter algorithm. Generally, therange interferometric filter assumes a constant slope terrain and the new generation offilters, even if they shift bandwidth with respect to the terrain slope, perform a spectralcul for the whole range line. In our approach, a sliding moving window is used to per-form a local adaptive range filter. Areas over critical baseline and shadowed areas for example can be detected and masked with this approach. During the process, an op-timisation is performed to perfectly align the local common bandwidths. Preliminaryresults show an improvement of the coherence over mountainous area under study,making it possible to exploit the InSAR data archive in this area.