Multidisciplinary approach for the characterization of a deep-seated landslide in a semi-arid region (Cañón de Yerbabuena, San Luis Potosí, Mexico)

Abstract

Multidisciplinary approaches for the characterization of deep-seated landslides (DSLs) are useful in comprehending the internal and external dynamics of the phenomena. This paper examines and characterizes the active Canon de Yerbabuena DSL (in Ahualulco, San Luis Potosi, Mexico), for which there are over 30 years of damage records to Federal Highway 63. Hence, the integrated study carried out includes lithological and structural characterization, geomorphological mapping, Persistent Scatterer Interferometry (PSI) analysis, and electrical geophysical surveys. The slope deformation extends over the highly weathered and fractured volcanic rocks of the Ahualulco Volcanic Complex in an area comprising 741,000 m2 and mobilizes an estimated rock volume of 6,950,459 m3. Geomorphological features within the DSL include a counter-scarp, minor scarps, tension cracks, small landslides, avalanche breccias, toppling, and colluvial deposits. Furthermore, the velocity rate in the upper section of the slope reaches up to 10 mm/year with a linear behavior that changes to a faster non-linear deformation (up to 30 mm/year) in the middle-lower part of the DSL. This change is the result of a multiple-complex dynamic linked to the presence of two normal faults fragmenting the middle section of the slope and an interbedded volcaniclastic clayey-siltstone layer acting as a possible sliding plane; the latter being defined by a resistivity survey. The acceleration of the velocity rates at the foot of the DSL are linked to torrential rains in the area and cause the most severe damage to the highway. Furthermore, the general slow deformation within the DSL is triggered by severe erosion from the seasonal river at the foot and the run-off on both flanks.