Landslides in Colombia and their impact on towns and cities

Each year landslides in Colombia cause loss of life and widespread damage to towns and cities. Many of the major cities, such as Bogotá and Medellin, have experienced rapid, uncontrollable expansion of the population over the past few decades, due to migration from the rural areas to urban centres. Due to the relatively high cost of living space, homes are built on the steep, middle and upper valley slopes which are susceptible to mass wasting. The slopes above Medellin have resulted in at least three known catastrophic landslides. The failure of thick residual soils, overlying intensely fractured bedrock, occurs during torrential
storms or following prolonged heavy rainfall. In 2003 for example, at least 13 persons were killed, 20 remain missing, and more than 300 homes were destroyed after overnight rains in western Colombian towns in the Caldas district. Landslides may also be induced by earthquakes, such as those which occurred in 1999 in the Eje Cafetero, central part of Colombia and in 1995 in Tauramena. These block roads, damage communications and
utilities and often isolating small towns. This has significant impacts on the economy preventing the export of crops such as coffee. Earthquake triggered landslides and volcanic landslides continue to be generated near Nevado del Ruiz and Nevado del Huila, volcanoes. It was a huge lahar in 1985, which buried the town of Armero killing at least 25,000 people. Small scale artisanal coal mining in Central Cordillera, in Antioquia, frequently results in subsidence of the ground surface and the generation of destructive landslides. Several cities
in Colombia have established legislation and organisations to mitigate against landslide hazards. The objectives of this paper are to draw attention to the causes, consequences and management of landslides in the towns and cities of Colombia.