TTE254

ABSTRACT

The present study focused on conducting a comprehensive analysis of the hazard posed

by lahars generated by the Lonquimay volcano, wich would affect the locality of

Malalcahuello, and assessing the degree of exposure of the infrastructure in this sector. Given

that lahars represent one of the most destructive volcanic threats, and considering the

proximity of the populated center to the volcano, there arises the necessity to carry out this

type of study to contribute to risk assessment, territorial planning, and emergency scenario

management.

To achieve this study, a review of existing scientific literature on geological and

volcanological background was conducted, along with an investigation into the historical

activity and morphological peculiarities of the valleys through which lahars could travel. This

was done to establish different possible eruptive scenarios and define the conditions under

which lahars would be generated. Subsequently, the numerical model “LAHARZ” was

employed to obtain potential lahar inundation areas based on the initial flow volume and a

digital elevation model.

Once the hazard was assessed, the exposure analysis was carried out, which involved

identifying areas where existing infrastructure is exposed to the studied danger. To do this,

data obtained from satellite images providing information about constructions in the sector

were integrated with the lahars flood hazard map.

The results obtained have demonstrated the significant capacity of eruptions to generate

lahars, even under conditions of low eruptive explosivity, especially during the winter season

due to snow cover on the volcano. Additionally, it was evident that there are high, medium,

and low hazard zones in Malalcahuello and its surroundings. The town of Malalcahuello

would not be directly affected by lahars as it is located in a low hazard and low exposure

zone almost entirely. However, it could be isolated due to the cutting off of access and

evacuation routes after the advancement of lahars. On the other hand, there are sectors around

the main locality that are in high hazard zones and exhibit a high level of exposure.

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