An InSAR‐GNSS Velocity Field for Iran

Abstract

We present average ground‐surface velocities and strain rates for the 1.7 million km2 area of Iran, from the joint inversion of InSAR‐derived displacements and GNSS data. We generate interferograms from 7 years of Sentinel‐1 radar acquisitions, correct for tropospheric noise using the GACOS system, estimate average velocities using LiCSBAS time‐series analysis, tie this into a Eurasia‐fixed reference frame, and perform a decomposition to estimate East and Vertical velocities at 500 m spacing. Our InSAR‐GNSS velocity fields reveal predominantly diffuse crustal deformation, with localized interseismic strain accumulation along the North Tabriz, Main Kopet Dagh, Main Recent, Sharoud, and Doruneh faults. We observe signals associated with recent groundwater subsidence, co‐ and postseismic deformation, active salt diaprism, and sediment motion. We derive high‐resolution strain rate estimates on a country‐ and fault‐scale, and discuss the difficulties of mapping diffuse strain rates in areas with abundant non‐tectonic and anthropogenic signals.

Open Access GNSS Data for Studies of the Lithosphere

“…InSAR can provide a more spatially dense estimation but is limited by temporal resolution (currently every week or so), only providing displacements or velocities in the direction of the line-of-sight of the satellite, which is at a high angle from the Earth's surface, and InSAR observations are nearly insensitive to northsouth oriented displacements or velocities because of the orbital geometry. Because of these limitations, the most comprehensive results are obtained when combining InSAR and GNSS data in some optimal fashion (e.g., M. Chen et al, 2024;Franklin & Huang, 2022;Maubant et al, 2022;Ou et al, 2022;Watson et al, 2024;W. Wu et al, 2024).…”