Satrio Muhammad Alif, Ongky Anggara, Arlina Surya Dinur
This study evaluates how correcting GNSS vertical velocities using viscoelastic postseismic and fault-locking elastic deformation models changes the interpretation of vertical land motion across Sumatra, Indonesia. A dataset from 87 GNSS stations was processed to obtain observed (original) vertical velocities, which were then corrected using modeled postseismic and elastic deformation effects. The comparison shows that correction increases the velocity range by approximately 13%, indicating stronger spatial variability of vertical land motion than previously recognized. Approximately 17.2% of stations changed velocity sign after correction, demonstrating that tectonic effects may mask or exaggerate subsidence or uplift when uncorrected data are used. The most significant corrected subsidence is observed in North Aceh (−105 mm/year), while the largest subsidence in the original GNSS velocities is observed in Medan (−72 mm/year), exceeding previously reported rates from InSAR-based studies. These findings emphasize the importance of integrating tectonic deformation models when interpreting GNSS vertical velocities in tectonically complex regions. The resulting vertical velocity map provides improved constraints for seismic hazard assessment, land subsidence monitoring, and climate-related coastal risk studies in Sumatra. © 2026 Editorial office of Geodesy and Geodynamics
Geomatics Engineering, Institut Teknologi Sumatera, Lampung, 35365, Indonesia