The Nevado del Ruíz volcano in Colombia’s Central Andes range is being carefully monitored by a Unified Command Post (PMU) that was set up between the country’s Emergency Risk and Disaster Response Unit (UNGRD), and Geological Service (SGCOL), after a week in which the 5,321 meter-high active volcano registered continuous “explosive activity.” The Volcanic Ash Advisory Center (VAAC) in Washington, warned that on Wednesday, the Nevado del Ruíz’s volcanic ash plume rose 6,100 meters (20,000 ft) into the atmosphere.
A Yellow Level of alert is being maintained despite the volcano’s “unstable behavior.” According to the Geological Service’s most recent media briefing, the Nevado del Ruíz’s “seismic activity continues to be intense, mainly related to the movement of fluids inside the volcanic conduits. This seismicity has been characterized by the occurrence of continuous volcanic tremor of low to moderate energy levels, tremor pulses, and very long-period earthquakes near the Arenas crater.”
Volcanic ash fall has been reported in the municipalities of Líbano, Herveo, Casabianca and Villahermosa (department of Tolima), Armenia and Filandia (department of Quindío), Pereira and Santa Rosa de Cabal (department of Risaralda) and Manizales, Villamaría and Chinchiná (department of Caldas).
The Nevado del Ruíz last erupted on November 13, 1985, killing 25,000, after lava melted the volcano’s ice caps and snow-covered summit unleashing a mud flow that buried the prosperous agricultural city of Armero, Tolima, under debris. The Armero tragedy is Colombia’s worst natural disaster.