Mechanical instability quantification of slopes at Cofre de Perote volcano, eastern Mexico

Resumen

Cofre de Perote (CP)
volcano is located at the eastern end of the Trans-Mexican Volcanic
Belt (TMVB) at 19°30’ Lat N, 97°10’ Long W. At a height of 4,282
m.a.s.l, it comprises one of the most massive structures within the
Citlaltépetl – Cofre de Perote volcanic range (CCPVR), which
constitutes an important physiographic barrier that separates the
central altiplano, also known as Serdán Oriental, from the coastal
plains of the Gulf of Mexico. This massive structure has repeatedly
collapsed, and at least two of the collapse events occurred long
after activity ceased, suggesting that even extinct volcanoes may
pose an important hazard to nearby populated areas. In the present
work, volcanic instability is approached through both quantitative
and descriptive methods that include combined numerical analysis of
limit equilibrium, calculated with Bishop’s modified method, and
finite element analysis. The combined techniques were applied after
attaining mechanical parameters in the laboratory, the field and
through careful geological observations in order to obtain a model
that approaches structural conditions prior to the destruction of
the volcano Reconstruction of the ancient volcano was used to
propose an instability model for the modern summit, where maximum
stress/ strain relationships before failure were determined for the
reconstructed section and actual volcano summit. Results obtained
from these models indicate that the volcanic edifice is still
unstable, could experience failure in the near future, and should be
considered for future hazard assessment.