2025/01/07 by Mohammadhossein Mohammadnia, Sanaz Vajedian, Zahra Mousavi +1 · 1 voice
Earth and Planetary Sciences · #earthquake and tectonic studies #Geological and Tectonic Studies in Latin America #Geological and Geophysical Studies Worldwide
paper · pdf · doi:10.1093/gji/ggaf012
SUMMARY Monitoring volcanic deformation is crucial for understanding volcanic behaviour, but challenges like limited global navigation satellite system (GNSS) coverage, infrequent synthetic aperture radar (SAR) data acquisitions, and coherence loss during eruptions complicate this task. Our study on the 2018 eruption of Sierra Negra utilizes Sentinel-1A/B images to track surface deformation patterns that revert to their initial state across three phases: before, during and after the eruption. We implemented an adaptive workflow using the shortest temporal baseline of consecutive SAR image pairs, including InSAR, optical flow and pixel offset tracking methods, to accurately capture surface displacement linked to the dynamics of the magma reservoir in the caldera and a nearby (sub-) horizontal dike. Results show that while the caldera subsided gradually over two months during lava flow (initially at a rate of several metres) until it began to uplift again, the northern region alternated between uplift and subsidence twice in the line-of-sight (LOS) direction. This pattern suggests repeated magma injections into the sub-horizontal dike sustained the lava flows from the northeastern fissure. The one-day difference between SAR images from ascending and descending tracks enabled us to estimate the underground magma transfer rate at approximately 60 m hr−1, which aligns with the magma migration trajectory indicated by seismic data. By integrating InSAR and offset tracking methods, we provide a comprehensive view of surface displacement throughout the volcanic eruption cycle.