Evaluation of the Effects of the 1985 Michoacan Earthquake on the Water Systems in Metropolitan Mexico City

During the Michoacan earthquake of September 19, 1985, the water supply and distribution systems of Metropolitan Mexico City were severely damaged. This paper investigates the type of damage, taking into consideration the characteristics of the earthquake and the peculiar soil and topographic conditions of the valley where the city is situated. It describes the water systems in the metropolitan area, the main features of the subsoil conditions and the engineering aspects of the earthquake, highlighting their relationship to lifeline earthquake engineering. The investigation concentrates on the damage statistics for the buried segmented pipelines in the water systems. It observes and explains the relatively low damage to lifelines in the epicentral region by analyzing and comparing ground motion characteristics there and in Mexico City. Finally, based on the analysis of this information, some recommendations are given to reduce the seismic vulnerability of the water systems in the metropolitan area.