Abstract—The Itasy Volcanic Field (IVF) is a monogenetic volcanic field located in the central highlands of Madagascar and is characterized by numerous volcanic cones displaying various geomorphological landforms. The IVF was a result of Pliocene to Quaternary volcanic eruptions and mainly composed of basaltic volcanic cones and trachyte domes. This paper aims to describe and to establish a geomorphological classification of basaltic volcanic cones within the IVF, based on their morphometric characteristics such as shape and diameter of the cone base; slope of the flanks of the edifice, and height of the crater relative to the cone base. Digital Elevation Model (DEM) data from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Shuttle Radar Topography Mission (STRM) were used, coupled with remote sensing data from Google Earth Pro and field investigation. DEM and imagery analyses and processing were performed using ArcGIS and Global Mapper. Five types of major basaltic volcanic landforms were identified within the IVF: semi-circular cones (e.g. Kasigie cone), representing 8.39% of the identified cones; symmetric and asymmetric horseshoes-shaped edifices (e.g. Mananasy and Fasia cones), which are the most dominant 74.8% of the cones; fissure cones (e.g. Mandetika cone) forming 5.34% of the cones; multiple clustered -shaped breached cones forming 6.1% of the volcanic cones (e.g. Ambohitritainerina cone) and single cone with multiple craters (e.g. Ambohitromby cone), which represent 6.1% of the cone. This contribution enables the characterization of morphological types of the volcanic cones within the IVF.

Index Terms—Itasy Volcanic Field, Digital Elevation Model, Cone morphology, Volcanic morphometry

Cite:Tsilavo Raharimahefa and Christine Rasoazanamparany, "Geomorphological Classification of Volcanic Cones in the Itasy Volcanic Field, Central Madagascar," International Journal of Geology and Earth Science, Vol. 4, No. 4, pp. 14-34, December 2018.