A. Pola

Bio: A. Pola is an academic researcher from National Autonomous University of Mexico. The author has contributed to research in topics: Volcano & Lava. The author has an hindex of 9, co-authored 18 publications receiving 386 citations. Previous affiliations of A. Pola include Universidad Michoacana de San Nicolás de Hidalgo & University of Milan.

Structural architecture of the Colima Volcanic Complex

Abstract: [1] The Colima Volcanic Complex (CVC) is currently the most active Mexican volcano and is located in the western sector of the Trans–Mexican Volcanic Belt, inside the active Colima Rift, a regional N-S-striking extensional structure. The Colima Rift is filled by a ∼1 km-thick sequence of quaternary lacustrine sediments, alluvium, and colluvium, mostly underling the about 3000-m-thick volcanic pile of the CVC. In this work we present the results of a detailed morphostructural and field study of Quaternary faults and fractures in the CVC and the surrounding area, including the regional structures of the Colima Rift. We also present a geometrical modeling of the faults inside the volcano and a numerical model of the gravity-induced stress and strain fields of the CVC. The study attempts to characterize the geometry, kinematics, and dynamics of the deformation features of the CVC and relate it with the volcano structure, the geology of the substratum, and the geodynamic setting of the region. Our model considers that the observed deformation of the CVC and the surroundings results from the interplay between the active N-S-trending regional extensional tectonics and the southward spreading of the volcano over its basement forming an E-W-oriented volcanotectonic graben. The interaction between regional tectonics and previously unrecognized volcanic spreading can control magma migration and flank instability, in an area where eruptions and sector failures represent a potential high risk for more than 500,000 people.

Geology of the Late Pliocene-Pleistocene Acoculco caldera complex, eastern Trans-Mexican Volcanic Belt (México)

Abstract: We present a new 1:80,000-scale geologic map of the Acoculco caldera (Ac) located between the states of Puebla and Hidalgo in eastern Mexico. The map, encompassing an area of 856 km2, is gr...

Cyclic and Fatigue Behaviour of Rock Materials: Review, Interpretation and Research Perspectives

Abstract: The purpose of this paper is to provide a comprehensive state of the art of fatigue and cyclic loading of natural rock materials. Papers published in the literature are classified and listed in order to ease bibliographical review, to gather data (sometimes contradictory) on classical experimental results and to analyse the main interpretation concepts. Their advantages and limitations are discussed, and perspectives for further work are highlighted. The first section summarises and defines the different experimental set-ups (type of loading, type of experiment) already applied to cyclic/fatigue investigation of rock materials. The papers are then listed based on these different definitions. Typical results are highlighted in next section. Fatigue/cyclic loading mainly results in accumulation of plastic deformation and/or damage cycle after cycle. A sample cyclically loaded at constant amplitude finally leads to failure even if the peak load is lower than its monotonic strength. This subcritical crack is due to a diffuse microfracturing and decohesion of the rock structure. The third section reviews and comments the concepts used to interpret the results. The fatigue limit and S–N curves are the most common concepts used to describe fatigue experiments. Results published from all papers are gathered into a single figure to highlight the tendency. Predicting the monotonic peak strength of a sample is found to be critical in order to compute accurate S–N curves. Finally, open questions are listed to provide a state of the art of grey areas in the understanding of fatigue mechanisms and challenges for the future.

Microstructural controls on the physical and mechanical properties of edifice‐forming andesites at Volcán de Colima, Mexico

Abstract: The reliable assessment of volcanic unrest must rest on an understanding of the rocks that form the edifice. It is their microstructure that dictates their physical properties and mechanical behavior and thus the response of the edifice to stress perturbations during unrest. We evaluate the interplay between microstructure and rock properties for a suite of edifice-forming rocks from Volcan de Colima (Mexico). Microstructural analyses expose (1) a pervasive, isotropic microcrack network, (2) a high, subspherical vesicle density, and (3) a wide vesicle size distribution. This complex microstructure severely impacts their physical and mechanical properties. In detail, porosities are high and range from 8 to 29%. As a consequence, elastic wave velocities, Youngs moduli, and uniaxial compressive strengths are low, and permeabilities are high. All of the rock properties demonstrate a wide range. For example, strength decreases by a factor of 8 and permeability increases by 4 orders of magnitude over the porosity range. Below a porosity of 11–14%, the permeability-porosity trend follows a power law with a much higher exponent. Microstructurally, this represents a critical vesicle content that efficiently connects the microcrack population and permits a much more direct path through the sample, rather than restricting flow to long and tortuous microcracks. Values of tortuosity inferred from the Kozeny-Carman permeability model support this hypothesis. However, we find that the complex microstructure precludes a complete description of their mechanical behavior through micromechanical modeling. We urge that the findings of this study be considered in volcanic hazard assessments at andesitic stratovolcanoes.