Today is November 13, 2010, meaning it has been 25 years since the tragic lahar that killed over 23,000 people (video, graphic at times) in Armero, Colombia. This lahar was generated by a fairly minor eruption of Nevado del Ruiz, but the resultant melting of snow and ice at the summit charged down the Langunillas River channel (along with a few tributaries) and destroyed the town of Armero (amongst other small towns). The biggest tragedy of this event was that it was so avoidable, but a number of events/factors lead to the townspeople not being warned soon enough to climb to higher ground and escape the lahars. This event has become a cautionary tale about the importance of volcanic monitoring and hazard response, and luckily it has had a positive effect. The Colombian Geological Survey (INGEOMINAS) set up multiple volcano observatories in Colombia after the eruption to help monitor the country's active volcanoes and lahar warning systems have been set up on many similar volcanoes worldwide to help give people the time they need to get to higher ground and escape the lahar. Remember, lahars are very channel-confined, so climbing as little as 100 meters uphill could be the difference between life and death when a lahar, traveling at 10-30 km/hr is heading your way. Nevado del Ruiz is still an active volcano, so hopefully when the volcano does erupt again, the country will be prepared.
This eruption, on a personal note, likely started me in the direction of studying volcanoes and volcanic eruptions. My mother's home town is Pereira, Colombia, to the southwest of Nevado del Ruiz. I remember driving through some of the area near the volcano a few years afterwards and it apparently left an indelible mark on me (remember, I was 8 when the lahar occurred). With any event with death of this magnitude, we always have to hope that good can come from it, and the eruption of Nevado del Ruiz in 1985 will likely end up saving more lives than it took 25 years ago.
Top left: Nevado del Ruiz, Colombia in an undated image.