Determining Ground Surface Deformation at Erta Ale Volcano and Assessing Lava Lake Reservoir Northern Afar, Ethiopia
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Date
2024-02
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Addis Ababa University
Abstract
This research endeavors to ground surface deformation analysis using Persistent scatter interferometry at Erta Ale volcano and assessing its Lava Lake reservoirs in northern Afar Ethiopia spanning the period from 2017 to 2022, using Sentinel-1A data. Erta Ale is an active volcano located tectonically at the triple divergent junction of the Arabian, Nubian, and Somalian divergent plates. Geological setting of Erta Ale is highly extended and thin crust layer which is additional factor to Era Ale volvcanic activity. Studying the ground deformation of actively erupted volcanoes at the local level is one way of monitoring the continental refits. In this study, 26 sentinel-1A descending single look complex (SLC) SAR data are the main input for the study. SAR data covers large areas that enables to generate densified Ground control points to assess surface displacement at active volcano area. The latest InSAR processing method, PS-InSAR, is used to process SAR data. The commercial software SARPROZ used to process and analyze data in PS-InSAR techniques. Atmospheric phase error are removed by the amplitude-phase scattering (APS) method in this method. In the subsidence area, maximum horizontal and vertical displacement are~143±1.2674 mm and~91.89mm, respectively. Areas including Bora Ale and areas in the NW of the north pits are continuously subsiding. In the Northeast, the deforming rate of subsidence is 13.76mm per year, resulting in ~12mm of ground contraction and vertical deflation ~40m. Between Ali Bagu and Boral areas, there are some boreholes and temporary cracking that cause depression of the earth’s surface. uplifting area is ~60.23 ±1.2674 and ~93.04 mm, respectively, in the SW direction, resulting in horizontal extension of PSC ~12cm. North pit Lava Lake magma has decreased in area from the February2017 to December 2022 is ~0.061723km2 to ~0.036983km2.
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Atmospheric phase scattering, Ground deformation, Persistent-scatter intefreometry, Ssubsidence, Uplift