Articles | Volume 372
Proc. IAHS, 372, 89–93, 2015
https://doi.org/10.5194/piahs-372-89-2015
Proc. IAHS, 372, 89–93, 2015
https://doi.org/10.5194/piahs-372-89-2015

  12 Nov 2015

12 Nov 2015

Surface deformation on the west portion of the Chapala lake basin: uncertainties and facts

M. Hernandez-Marin1, J. Pacheco-Martinez1, J. A. Ortiz-Lozano1, G. Araiza-Garaygordobil1, and A. Ramirez-Cortes2 M. Hernandez-Marin et al.
  • 1Departamento de Geotecnia e Hidráulica, Universidad Autónoma de Aguascalientes, Aguascalientes, Mexico
  • 2Doctorado en Ciencias de los Ámbitos Antrópicos, Universidad Autónoma de Aguascalientes, Aguascalientes, México

Abstract. In this study we investigate different aspects of land subsidence and ground failures occurring in the west portion of Chapala lake basin. Currently, surface discontinuities seem to be associated with subsiding bowls. In an effort to understand some of the conditioning factors to surface deformation, two sounding cores from the upper sequence (11 m depth) were extracted for analyzing physical and mechanical properties. The upper subsoil showed a predominant silty composition and several lenses of pumice pyroclastic sand. Despite the relative predominance of fine soil, the subsoil shows mechanical properties with low clay content, variable water content, low plasticity and variable compressibility index, amongst some others. Some of these properties seem to be influenced by the sandy pyroclastic lenses, therefore, a potential source of the ground failure could be heterogeneities in the upper soil.

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Short summary
This research contributes to the understanding of surface deformation in the study area with new knowledge of the upper soil sequence. An established sequence distribution of the shallow layers was set and some of their geotechnical properties were determined. The analized samples are composed by compressible clayey silt and several lenses of volcanic sandy ash. Heterogeneities may be contributing to differential subsidence which is controlling the occurrence of surface faulting.