The impact of present lahars on the geomorphologic evolution of proglacial gorges: Popocatepetl, Mexico

Popocatepetl (19°03′N, 98°35′W; 5450 m) is located 70 km southeast of Mexico City. The volcano resumed its eruptive activity in 1994 with emissions of pyroclasts that partially melted the glacier located on the north face. The sudden release of water generated large lahars that flowed downslope though proglacial gorges. This paper examines the geomorphologic evolution of these gorges since 1992 and focuses particularly on the landforms created by the most recent lahars of July 1997. The research suggests that the transport capacity of the lahars has increased despite the fact that the sediments they carry originate in deposits formed by earlier processes. The presence of continuous permafrost in the area is a key factor in the formation of lahars.