Integrated PS-InSAR and SBAS InSAR for Lava Dome Collapse Detection: Case Studies from Mt. Merapi Zahratunnisa (1*), Asep Saepuloh (2), I G. B. Eddy Sucipta (3)
(1) Student, Faculty of Earth Sciences and Technology, Bandung Institute of Technology (ITB), Indonesia.
(1) Lecture, Geology Engineering Study of Earth Science Engineering Department, Universitas Syiah Kuala, Indonesia.
(2) Professor, Faculty of Earth Sciences and Technology, Bandung Institute of Technology (ITB), Indonesia.
(3) Professor, Faculty of Earth Sciences and Technology, Bandung Institute of Technology (ITB), Indonesia.
*zahratunnisa[at]usk.ac.id
Abstract
Lava domes at stratovolcanoes can evolve through stable and unstable structural phases, with transitions that are often gradual but can lead to sudden hazardous events. One of the most dangerous consequences of dome instability is collapse, which may trigger pyroclastic flows, among the deadliest volcanic hazards. This study focuses on understanding lava dome deformation as an early indicator of potential collapse by integrating Permanent Scatterers InSAR (PS-InSAR) and Small Baseline Subset InSAR (SBAS-InSAR) techniques. Using temporal Sentinel-1 SAR imagery, we investigated ground deformation at Mount Merapi, an active stratovolcano in Indonesia. At Mt.Merapi, a new lava dome began forming within the summit amphitheatre left by the 2010 climactic eruption, and continued to grow under the persistent influence of pyroclastic density current (PDC) activity since 2018. The integrated InSAR approach addresses the limitations of the individual techniques: PSInSAR exhibits ~12.5% higher coherence but lower point density, whereas SBAS offers denser spatial coverage but is prone to temporal error accumulation. Combining both methods enables high-resolution spatiotemporal monitoring of surface deformation and enhances our ability to detect precursory signals to dome collapse.This research demonstrates the value of satellite-based remote sensing in characterizing dome instability and supports improved hazard assessments for strato-volcanic systems.
