Assessment of Recent Lava Flows and Land Surface Temperature Using Geospatial Tools At Erta ‘Ale Volcanic Range, Afar Rift, Ethiopia
No Thumbnail Available
Date
2018-05-03
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
Assessment of Recent Lava Flows and Land Surface Temperature Using Geospatial Tools at Erta ‘Ale Volcanic Range Afar Rift, Ethiopia.
Tekalign Gebreyesus, MSc. Thesis
Addis Ababa University, May 2018
Volcanoes are generally found where tectonic plates are diverging or converging. Volcano lies on top of a rupture in the crust of Earth that allows hot lava, volcanic ash, and gases to escape from the magma chamber below the surface. This study is carried out in Afar Depression, north eastern part of Ethiopia specifically on Erta ’Ale volcanic range as it is an area of active extensional deformation and basaltic volcanism taking place. Volcanism results a natural hazard that can cause damages in properties and loss of life. Studies indicate that 9.5 million people live within 30 km proximity of this active volcano in Ethiopia. The objective of this study is to assess and map recent lava eruptions and land surface temperatures from Erta’ Ale volcanic vents during the year 2017 using geospatial tools. The data layers used in this research were Landsat-8 and Sentinel2-A multispectral high-resolution satellite images. The methods used are geospatial object-based image classification using eCognition software for recent lava flow mapping and Single-Channel Algorithm (SCA) for Land surface temperature estimation. The requirements for SCA in this study were normalized difference vegetation index (NDVI) based land surface emissivity and at sensor brightness temperature calculation. The result of LST was mapped. This result was also validated by the MODIS Terra LST products for each result. The recent (2016−2017) volcanic lava eruptions were also mapped and the result indicates, in general, there was no lava eruption in 2016 rather the lava lake rising to the rim and falling. The volcanic lava eruption started in January 2017 from the southern crater of Erta ’Ale lava lake and then followed by the development of a new fissural vents and lava eruption on the southern part of Erta ’Ale volcano within 4.5 km. This lava eruption continued until December 2017 and the resulting lava flows have been mapped. The lava flow directions of the eruptions are eastward and westward from the vent. The area of lava flow field was calculated in square kilometer from no flow to the youngest lava flows with maximum area coverage of 24.24 km2. The calculated lava flow field was positively correlated with the maximum value of land surface temperature distribution.
Description
Keywords
Erta Ale Volcano, New Fissure Eruption, Recent Lava Flow, Sentinel-2A