Nevado del Ruiz is a 5389-metre high volcano in colombia , South America. the town of Armero is 74 kilometres away. the volcano had erupted befor , in 1845. that eruption killed hundreds of people in Armero. But , by 1985 , most people had forgotten about the dangers of the volcano and the town's population had grown to almost 30000. Scientists had know for over a year that the volcano was active , but when they tried to warn people of the danger , nobody believed them.