It’s been raining all night and sometimes the rain has been very heavy, pounding on the corrugated plastic roof of my small room. It is making me think more urgently of the favelas and their situation. Following what Paulo Saad was telling me yesterday, I have been reading a very interesting and worrying article by Schuster et al. in a book on landslides. The combination of the climate (heavy rains from January to March) and underlying geology (steep weathered granite slopes and residual soil on top) makes Rio particularly susceptible to landslides. Combined with the prevalence of illegal and unsafe building spreading further to higher and steeper slopes, you have a real recipe for disaster: simple landslides can become debris flows as more material accumulates into the slide and adds to its weight and destructive capacity.
In 1966 and 1967, there were over 1000 deaths from landslides after particularly heavy rain in the Rio area. Santa Teresa was also badly hit by last series of catastrophic landslides to affect Rio in 1988, when the Santa Genoveva Hospital for elderly people was destroyed, killing 34. Altogether 120 people were killed and, perhaps even more worrying for future development, 22,000 were made homeless. According to sources quoted by Schuster et al., this was after less than an hour of particularly heavy rain…
After the late 1960s events that action was taken to reforest the undeveloped slopes around Santa Teresa and reinforce some parts of the hill with concrete channels to direct the flow of water. Building regulations were also strengthened. However, it is in this area that much of the recent illegal building is taking place – and as I mentioned, not just by the desperate and ignorant poor, but also by simply greedy and uncaring middle classes.
Robert L. Schuster, Daniel A. Salcedo and Luis Valenzuela. Overview of catastrophic landslides in South America in the twentieth century, pp.1-34 in Catastropic Landslides: Effects, Occurrences, Mechanisms. ed. Stephen G. Evans and Jerome V. DeGraf, Geological Society of America, 2002.