Spontaneous Transient Summit Uplift at Taftan Volcano (Makran Subduction Arc) Imaged Using an InSAR Common-Mode Filtering Method

Abstract

We unambiguously document unrest at Taftan volcano. Summit uplift was detected using Interferometric Synthetic Aperture Radar time series and its timing tightly constrained applying a new common mode filtering method. Uplift started and ended gradually lasting 10 months (July 2023 to May 2024). Uplift peaked at 11 cm/year rates, and during slowing-down several gas emission events occurred. Unrest was triggerless, uncorrelated with rainfall or seismic events. We favor internal driving processes with two possible scenarios: (a) dynamic hydrothermal alteration leading to permeability changes, shallow gas storage and pressurization, followed by opening of degassing pathways; or (b) a minor, undetected deep magmatic intrusion causing volatile exsolution and pore pressure increases within the hydrothermal system. Lack of post-unrest subsidence suggests persistence of hydrothermal high-pressure conditions at the summit and associated hazards. Our study shows how satellite imagery reveals hidden volcanic hazards at Taftan, and the need to implement a holistic volcano risk reduction strategy.