On 12 December 1979 a disastrous tsunami occurred, for the second time in the twentieth century, on the coast of Nariño and Cauca (SW-Colombia), generated by a 8.4 magnitud earthquake in the nearby subduction zone. The diverse consequences of this earthquake -strong shaking, tsunami and soil liquefaction- caused great human and material losses, however limited due to circumstances such us sparse population, low tide level and dominant buildings types. At international level this event singled out leading to important seismological results; at national level the disaster was the starting point for a process of scientific, technical, social and administrative advances, evident in the present status of the National Tsunami Prevention Program. This article describes some general characteristics of the tsunami phenomenon and of the present knowledge and forecasting capacities; it presents tha main features of the 1979 event, its previous occurrences, consequences, pending scientific problems regarding the tsunami hazard on Colombian coasts, as well as advances and needs in the control of the growing risk it entails.

Key words: Tsunami, Pacific Ocean, Colombia