The use of UAV represents a very useful tool for rock mass characterization, particularly in large, unsafe, and not accessible areas characterized by a complex geometry. This investigation was mainly focused on mapping discontinuities and characterizing rock masses using UAV photogrammetry, machine learning, including different algorithms, and intact rock laboratory analyses, respectively. To this aim different outcrops from those described as a part of the basement of the Acoculco Caldera Complex, composed by a series of folded limestones were selected. The results indicate that geomechanical and physical properties, together with outcrop information are very important to assign suitable properties to large rock units. In turn, the great number of plots of discontinuity orientation extracted from the 3D point cloud data by the used of our code written in python language allowed to easily identify the presence of a total of seven discontinuity sets, some of them related to the bedding sequence and some others related to shear and tensile stress due to folding.

The mechanical behavior of ignimbrites is crucial for applications in geotechnical engineering and natural hazard assessment. This study investigates three lithofacies of the La Escalera ignimbrites, characterized by varying degrees of welding and granular textures, to understand the influence of these factors on their mechanical properties and failure mechanisms. Using uniaxial compressive strength (UCS) tests and numerical simulations with the Particle Flow Code (PFC^2D), we analyzed the effects of welding degree and texture on the ignimbrite mechanical response. The experimental results revealed variations in UCS, Elastic Modulus (E), and Poisson ratio (υ), which were employed to calibrate the PFC^2D models. These models effectively replicated the stress-strain behavior and fracture patterns observed in laboratory tests for lithofacies with lower degrees of welding. However, the model showed less precision in capturing the mechanical behavior of the highly welded lithofacies, suggesting that its reduced granularity requires more advanced calibration techniques. Our findings reveal that a higher degree of welding enhances strength and brittleness, leading to distinct mechanical responses under stress. This study confirms the reliability of PFC^2D in simulating the complex behavior of volcanic rocks and highlights the need for model refinements to better represent highly welded ignimbrites. These insights are crucial for improving predictive models in geotechnical applications involving ignimbrites, contributing to the safer design and management of infrastructure in volcanic regions.

Slope instability in the Butterfly Biosphere Reserve (RBMM) Michoacán, Mexico, is a widespread phenomenon that results from the complex interaction among different factors such as climate, slope, and the spatial distribution of different rock units. The climate is temperate subhumid, with rains in summer and an annual average rainfall of 700 to 1250 mm. The main physiographic units of the area are volcanic mountains, with slopes greater than 30 degrees. The main scope of this study is to characterize the physical-mechanical properties of fresh and completely altered lower Miocene andesitic lavas of the Sierra de Angangueo (Cerro El Campanario, province of El Rosario, Michoacán) by implementing laboratory tests (bulk density, permeability, porosity, uniaxial compressive strength). The fresh rock sample presents total porosity, permeability, and UCS values of 0.262 mD, 17.1 %, and 63.5 MPa, respectively. Instead, the altered rock display values of 393.71 mD, 60.9 %, and 0.26 MPa. Our results suggest that the slope and the degradation of the rock properties induced by alteration are the conditioning factors of instability in the region. Atypical rainfalls may act as triggering mechanism for slope failure.