Boletín de la Sociedad Geológica Mexicana

Volumen 69, núm. 1, 2017, p. 243 ‒ 260

Evaluación probabilística del peligro por lahares en el flanco NE del Volcán Popocatépetl

Diana Marcela Rodríguez Espinosa1,*, Gustavo Córdoba Guerrero1, Hugo Delgado-Granados2

1 Grupo de investigación en riesgos, amenazas y medio ambiente GRAMA, Universidad de Nariño, Ciudad Universitaria, Torobajo, Pasto, Colombia.
2 Instituto de Geofísica, Universidad Nacional Autónoma de México UNAM, Circuito de la Investigación Científica S/N, Ciudad Universitaria, Delegación Coyoacán, Ciudad de México.

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Abstract

This study shows the results of a probabilistic evaluation of laharic hazard to Santiago Xalitzintla, locality in Puebla, at the NE flank of the Popocatépetl volcano in México. The TITAN2F software was used for lahars modeling. The program forecasts were compared with data obtained in the field for the laharic event of 2001 in order to evaluate the reliability of its use on a digital elevation model. The results obtained with TITAN2F are comparable with information reported previously in other studies of this lahar; coming to the conclusion that modeling with TITAN2F is reliable. This investigation provides a useful tool for the knowledge of laharic hazards. Also, it shows the probability of the affected area by inundation as well as the probability distribution of dynamic-pressure levels, which is an important parameter for assessment risk in a lahar flow.

To make a probabilistic analysis is required a number of statistically representative hypothetic scenarios, covering all possible cases. According to historical events recorded, two possible sources for a laharic flow were defined, and they correspond to the Huiloac and Alseseca gorges. Based on the geological information, the ranges of initial conditions that TITAN2F requires (velocity, concentration and volume) were defined for each one of the basins.

A stratified sampling was carried out using the Latin Hypercube method (LHS). This method generates a representative sample of hundreds of combinations from the initial conditions, in order to modeling laharic events with TITAN2F. The probabilistic analysis was made through Bayesian inference, and programming routines in OCTAVE. The probabilistic distribution indicates that there is a nearly 80 % probability to be reached by lahars at community areas of Santiago Xalitzintla. However it is characterized by low dynamic-pressure levels. The final section of the Huiloac gorge was identified as a critical zone, where the probability that dynamic-pressures surpassing destructive levels is high.

Keywords: Popocatépetl volcano, lahar, TITAN 2F, Santiago Xalitzintla, dynamic pressure, modeling software.