Resumo

GOMEZ CASTILLO, Gemma; FUENTES JUNCO, José de Jesús Alfonso  e  NAVARRETE PACHECO, José Antonio. Landslide risk analysis of the Tancítaro Peak and its zones of influence. Invest. Geog [online]. 2023, n.112, e60764.  Epub 22-Abr-2024. ISSN 2448-7279.  https://doi.org/10.14350/rig.60764.

Mass removal processes (MRP) arise from instability and changes in the characteristics of the Earth’s surface. The possibility of occurrence of these phenomena is accentuated in volcanic environments due to their morphological, lithological and tectonic characteristics.

To the southwest of the Michoacán-Guanajuato Volcanic Field is located Pico del Tancítaro, which is a stratovolcano that began its activity at the end of the Lower Pleistocene and is considered extinct. This volcano suffered two large debris avalanches more than 200,000 years ago, triggered by tectonic and magmatic activity. At present it continues to present small landslides and mudflows, generally triggered by heavy rains in areas of high slopes. Considering the above, the objective of this research is to identify and quantify the DRP risk in the surroundings of Pico del Tancítaro by determining hazard zones and analyzing vulnerability. In addition, the exposure to floods due to the proximity to riverbeds is analyzed, given the overflows that have occurred in recent times, which have generated disasters in nearby localities.

The integral analysis of the risk due to PRM was carried out in three phases. The first part involved a hazard assessment: a) recently occurred MICs (1995-2021) were recognized and inventoried; b) areas prone to collapse were identified through visual inspection and interpretation, based on high slopes and proximity to river gullies and steep slopes, using a 1 km x 1 km grid as a guide for progress, which translates into 469 cells and a total of 411. 22 km2 analyzed; c) 11 simulations of probable debris avalanches were elaborated with the Titan2D software, where the starting points of the simulations were chosen taking into account the factors of high slope, availability of material, proximity to localities and, mainly, previous presence of PRM in the contiguous areas; d) the proximity to riverbeds was considered as areas exposed to flooding, for this purpose the micro-basins and the water network were generated, and the latter was hierarchized by Strahler stream order and exposure buffers were assigned according to the order of the riverbed (order 1 = 5 meters distance, 2 = 10 meters, 3 = 20 meters, 4 = 30 meters and 5 = 50 meters to each side of the riverbed). For floods, no hazard analysis was performed, only exposure analysis.

The second part was the analysis of vulnerability by exposure, sensitivity and resilience of people, infrastructure and natural and agricultural resources, which was carried out by processing different databases, mainly the National Population and Housing Census 2020. In addition, a survey was designed to identify the level of risk perception, which was carried out through the application of a questionnaire among the inhabitants, specifically those settled in hazard zones.

In the third part, the previously mentioned layers were crossed, obtaining five levels of risk, from very low to very high. The risk of landslides is considerable in the southeast of the study area (towns in the municipality of Nuevo Parangaricutiro). The localities with the highest exposure to flooding are Peribán, Zirimondiro, Santa Ana Zirosto, Araparícuaro and Choritiro.

For the study area, high levels of PRM occurrence and a high and increasing susceptibility to flooding were identified; therefore, the Tancítaro Peak should be considered a danger zone for hydrogeomorphological phenomena. In addition, this work considers the high slopes, geology, land use change and heavy rainfall in the area as determinants for its high hazard. In addition to the above, we have high levels of vulnerability in some localities and blocks, which contributes to increased risk levels; moreover, it has been identified that there is a population that does not perceive the risk, despite having recently experienced a disaster or living in a very high hazard area (fully recognized by other residents and the authorities).

Finally, it is recommended that changes in land use be avoided, especially in areas where MICs have occurred in recent years (southeastern part of the study area), since this may contribute to the occurrence or acceleration of these phenomena and the economic and infrastructure repercussions may be increasingly greater. Information, preparedness and training are essential in this area to reduce vulnerability and thus disaster risk.

Palavras-chave : Peribán; landslides; floods; disaster; risk perception.