Lahar Formations and Gis-Based Analysis of Lahar Susceptibility in the Mountain Ararat Volcanic Massif

Abstract

Lahars, which can create disaster-scale impacts in strato-volcanic areas, are a type of mass movement specific to volcanic topographies. Lahar flows, which can be hot and cold in character, have frequently occurred on Mount Ararat in the recent geological past. Especially the presence of abundant coarse detrital material and thick pyroclastic deposits in the mobilized mass are the main parameters responsible for the transformation of debris flows into lahars. High slope values, developed surface drainage network, seismic as well as volcanic activity and tectonic deformation are also important factors. Climatologically, the melting of the Greater Ararat glacier, overflow of supraglacial lakes and heavy rainfall, which has tended to increase in recent years, control the lahar flows. In this study, in addition to explaining the mechanisms controlling lahar development, a lahar susceptibility analysis of the volcanic massif was performed using the GIS-based frequency ratio method. The results show that the potential for lahar development is high in a large part of the mass. Considering the presence of many rural settlements on the slopes of Mount Ararat Volcanic Massif, it is recommended that the lahar hazard should be included in the national disaster inventory and the spatial organization should be shaped accordingly.