On Nov. 13, 1985, a massive mudslide devastated entire towns and killed thousands in Colombia following the volcanic eruption of Nevado del Ruiz.

Shortly after 3 p.m. on Nov. 13, 1985, there was a violent steam explosion from the volcano. Authorities, believing that the explosion wasn’t serious, directed nearby residents to remain in their homes. At 7 p.m., the Red Cross ordered an evacuation, but it was soon called off because the volcanic activity appeared to be stopping.

At 9:08 p.m., Nevado del Ruiz began erupting molten rock, causing pyroclastic flows to spread across the peak’s ice caps. Unfortunately, a storm above the volcano blocked the eruption from the view of the people below.

The ice caps rapidly melted, swelling the nearby river and spurring catastrophic floods and mudslides. “As these floods of water descended the volcano, they picked up loose debris and soil from the canyon floors and walls, growing both in volume and density, to form hot lahars,” explains the U.S. Geological Survey’s Cascades Volcano Observatory.

The lahars, moving up to 50 kilometers per hour, hit the town of Armero over two hours after the eruption. “In a few short minutes most of the town was swept away or buried in a torrent of mud and boulders, and three quarters of the townspeople perished,” says the Cascades Volcano Observatory.

The flows also devastated the town of Chinchina, tearing down eight bridges and cutting the town off from the major city of Manizales. It also destroyed Chinchina’s coffee crop, leaving thousands without jobs.

All told, the volcano released about 20 million cubic meters of hot ash and rocks. The ensuing volcanic flows killed 23,000 people, injured 4,500 and left 8,000 homeless.

As a Columbian National himself, Chucho Merchan organised a benefit relief concert at The Royal Albert Hall on the 9th February 1986, 25 years ago. Chucho Merchan was known to most as the bass player and band member of The Pretenders, and then went on to join the Eurythmics Revenge band. Amongst the many performers were Annie Lennox, Chrissie Hynde, Pete Townsend, Dave Gilmour and The Communards.  Annie first performed a solo of the Stevie Wonder classic “Blame It On The Sun” and then performed an amazing duet between Annie and Chrissie Hynde was performed at the Colombian Volcano Relief Concert at the Royal Albert Hall in London on February 9, 1986. The song is a cover of the classic KC & The Sunshine Band hit.