Popocatépetl is one of the most active volcanoes and the second highest peak in Mexico, after the Pico de Orizaba. It has had more than twenty major eruptions since the arrival of the Spanish in 1519. Popo is currently active. A major eruption occurred in 1947 to begin this cycle of activity. Then, on the 21st December, 1994, the volcano spewed gas and ash which was carried as far away as 25km by prevailing winds. The activity prompted the evacuation of nearby towns and scientists began monitoring for an eruption. In December 2000, tens of thousands of people were evacuated by the government based on warnings from the scientists. The volcano then made its largest display in thousands of years. Popo is only 70km to the south-east of Mexico City, from where it can be seen regularly, depending on atmospheric conditions.