Urban patterns and disaster risk: The informal city on the hills

The magnitude of disasters depends on the natural hazard and the physical and socio-economical fragility to which a human settlement is exposed. While hazard indicators refer to the natural conditions of a place (precipitation, soil conditions, etc), indicators of vulnerability derive from the interaction nature-human activities, i.e. urbanization patterns. Having this as our initial assumption, this work explores urban configuration as a potential vulnerability indicator of landslides in the hills of Mexico City, which from the second half of the 20th century, have been gradually and informally settled. Although some efforts have been made to develop socio-economical vulnerability indicators (population density, income, dwelling materials, etc.), conditions related to the urban morphology of these territories under threat, remain unexplored. This research focused on two of the most representative cases in Mexico City where material and human losses took place as a result of hydro-meteorological disasters related to flooding and landslides. This type of disasters are expected to increase in this environment of continuous informal growth and climate change. Taking the Space Syntax Theory as interpretative basis, the results helped us conclude that the occurrence, location and magnitude of landslides are not solely related to the socio-economical vulnerability of these places, but also to the urban layout. Hence, the findings of this research open the doors for architects and urban planners to get more involved in new risk and vulnerability analyses, founded on different viewpoints.