SLOPE SLIDING ASSESSMENT AT CERRO EL CHIQUIHUITE, MEXICO CITY

Cerro El Chiquihuite is part of the Sierra de Guadalupe, a volcanic range in northern Mexico City. As in many other sites in the region the skirts of the mountain is heavily populated by more than 10,000 people. In October 1998 a rock block fell from the eastern cliff, and the geological reconnaissance made during that time suggested the possible presence of a slope sliding process in the making. Evidences for this process were the tilting of electric poles, damage to house structures, and damage to water piping underground among others. For a better recognition of the sliding process, if active, several studies have been performed. Particularly important are the drilling of 4 boreholes. 2 boreholes were drilled to be used for inclinometry and 2 other for piezometric checks. The inclinometers were built in 25 meters deep boreholes at the sites where maximum deformation would be expected. The piezometers were emplaced in 20 meters deep wells and consisting of 3 bulbs at different depths and independent from each other. At the same time, leveling work has been performed along a line in order to recognize possible associated sinking. The observation period is still limited (less than a year) and the measurements are still within instrumental error. Monitoring the western slope of Cerro El Chiquihuite continues every month or two and further work may reflect the possible presence of the sliding process but no firm results are expected before the completion of a complete year of measurements, but surely after a longer observation period.