When was nevado del ruiz formed?

Nevado del Ruiz, a stratovolcano in Colombia, was formed approximately 1.5 million years ago through volcanic activity. Its most recent significant eruptions occurred in the 20th century, notably the catastrophic eruption in 1985 that triggered a deadly lahar, resulting in the destruction of the town of Armero. The volcano continues to be an active geological feature, posing risks to nearby communities.