Nevado del Ruíz volcano still “unstable” despite change in risk levels

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Capture of the Nevado del Ruíz's incandescent plume of ash on July 2, 2023. Credit: Telecafe

After more than three months of being under an Orange Alert for an “imminent eruption,” Colombia’s Nevado del Ruiz volcano has seen a reduction in risk level as the country’s Geological Service (SGC) lowered it to Yellow. However, shortly after this announcement, on July 4, a vibrant red fumarole illuminated the night sky, as captured by seismic monitoring cameras.

During the night of July 4, a powerful incandescent light emanated from the one of the Nevado del Ruíz’s volcanic vents located near the Azufrado River Canyon. The Cañón del Río Azufrado is only 4 km from the Arenas crater. The first images taken at 20:48 pm were recorded by the local network Telecafe. Several hours later – July 5 (1:49 am) – the SGC registered a second ash emission indicating the continued state of instability within the volcano and the possibility of further surface events.

Residents of the capital of Caldas, Manizales, have captured impressive images of ash plumes rising from the snow-capped peak since the Nevado del Ruíz was placed on Orange Alert late March. Due to the mountain’s precarious state, characterized by the release of gases and ash with temperatures surpassing 450°C, the SGC issued a warning for local populations to stay away from the volcano’s Arenas crater. The SGC emphasized that the diverse intensities of colors emitted by the hot materials and gases originate from various sources, each with its own explanations.

In an official statement, the SGC highlighted the importance of remaining vigilant regarding the volcano’s evolution, despite the recent lowering in the risk level.

Screen capture by the SGC of a second ash emission from the Nevado del Ruíz volcano.

Rising to an elevation of 5,321 meters (17,457 feet), the volcano is situated within Los Nevados National Natural Park, attracting visitors with its scenic beauty and outdoor recreational activities. The history of volcanic activity at Nevado del Ruiz dates back thousands of years, with the earliest recorded eruption occurring around 3,000 years ago. Over the centuries, the volcano has experienced numerous eruptions, some of which have been significant and highly destructive.

The most catastrophic eruption of Nevado del Ruíz occurred on November 13, 1985. During this event, a lahar—a destructive mudflow composed of volcanic ash and debris—descended from the glaciated summit, devastating the town of Armero in the Magdalena river valley. Colombia’s worst natural disaster resulted in the loss of approximately 22,000 lives, making it one of the deadliest volcanic eruptions of the 20th century.

Following the 1985 eruption, monitoring and surveillance systems were significantly improved to mitigate the risks associated with Nevado del Ruíz. The Colombian Geological Service closely monitors the volcano, providing regular updates on its activity and alert levels to protect nearby communities and ensure early warning in case of potential eruptions.