Pasto, officially San Juan de Pasto, is the capital of the department of Nariño, in southern Colombia. Pasto was founded in 1537 and named after indigenous people of the area. In the 2018 census, the municipality had a population of 392,930. Pasto is located in the Atriz Valley on the Andes cordillera, at the foot of the Galeras volcano.

Galeras is an Andean stratovolcano in the Colombian department of Nariño, near the departmental capital Pasto. Its summit rises 4,276 metres (14,029 ft) above sea level. It has erupted frequently since the Spanish conquest, with its first historical eruption being recorded on December 7, 1580. A 1993 eruption killed nine people, including six scientists who had descended into the volcano's crater to sample gases and take gravity measurements in an attempt to be able to predict future eruptions. It is currently the most active volcano in Colombia.