The Chaman Fault (CF), which stretches 700 km in length, marks the western edge of the plate boundary that separates the Eurasian and Indian plates. While the CF exhibits both creeping and locked segments, but historically experienced only a few moderate size earthquakes. To understand the tectonic setting around the CF and its behavior, I created a high-resolution 3D velocity field and strain rate field by combining the Interferometric Synthetic Aperture Radar (InSAR) data from the Sentinel-1A/B in both ascending and descending orbits with the published nine GNSS campaign-mode velocities from 2008 to 2012. The study utilized published GNSS campaign-mode velocities from 2008 to 2012, comprising data from nine stations. Initially, I downloaded all relevant interferograms from the LiCSAR portal. Using LiCSBAS software and adopting the Small Baseline Subset (SBAS) method, I constructed the Line of Sight (LOS) displacement time series spanning from October 2014 to September 2023. The least-squares approach was used to estimate the LOS velocities for every consistent pixel. Across the CF, seven profiles were taken in both ascending and descending LOS at various locations. The velocity profiles demonstrate a clear change in velocity across the CF and type of fault deformation, with the ascending LOS 0 to 7 mm/yr and the descending LOS 0 to 2 mm/yr velocities difference. To perform the 3D velocity inversion, I combined the InSAR and GNSS data and eliminated the long-wavelength noise first. The resulting velocities from the inversion demonstrate differences on either side of the CF and velocity components indicating strike-slip movement along CF. After that, I choose five profiles across the CF using the inversion velocity data to assess both fault-parallel and fault-normal displacement. These profiles exhibit velocity change, as can be seen in Profiles 2 and 3, sharp velocity gradients across the CF show that the fault is continuously creeping at the rate of 10 to 14 mm/yr in the Nushki and Tarnak Rud areas. The arctangent pattern indicates a slip rate of 9 mm/yr and a locking depth of 4 km in Profile 3, corresponding to a 95 km locked segment of the CF, with the potential to generate a 6.5 Mw earthquake in 100 years. Then, using the horizontal and vertical velocities, I calculate the strain rate and tilt rate, respectively. The strain rate field map highlights significant localized deformation along the CF, particularly in the Nushki and Tarnak Rud areas, while the tilting rate field map from vertical velocity data shows tilting zones, particularly between 29.5°N and 30.5°N the eastern side of CF. The tilt rate indicates that there is no significant vertical movement along the fault. Overall results indicate that the CF is locked as well as creeping, where a locked section could weaken the velocity and result in large earthquakes, whereas the creeping section could strengthen the velocity which results in a low-stress regime.

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