Fast hazard evaluation employing digital photogrammetry: Popocatépetl glaciers

Abstract

Lahar floods are among the main hazards originated by ice and snow melting during eruptions of glacier-clad volcanoes. Hazard evaluation can be fast and safe by using remote methods such as digital photogrammetry, using software for image processing of scanned aerial photographs. Digital photogrammetry also allows monitoring of the evolution of geological processes.
Before the onset of the current eruptive activity, Popocatépetl glaciers were studied by direct methods. After December 1994, it became necessary, for safety reasons, to find a remote method to continue with the study of glacier changes. In this paper, a hazard evaluation methodology is discussed and applied to measurement of glacier areas at Popocatépetl on December 2000 with the aim to determine equivalent water volume and to estimate maximum and minimum laharic volumes for different ice- melting scenarios. Our results show that even a 100% ice melting would not produce a laharic event of the size of the catastrophic lahars at Nevado del Ruíz or San Nicolás.