Servicio Geológico Colombiano’s (SGC) reported that at 1713 on 11 April a seismic signal at Nevado del Ruiz was recorded along with an ash, gas, and steam plume. The plume rose almost 3.3 km above the summit and drifted N, causing minor ashfall around the volcano as reported by Parque Nacional Natural Los Nevados staff. It was also visible in webcam images and from the city of Manizales, 28 km NW. The Alert Level remained at 3 (Yellow; the second lowest level on a four-color scale).

Geological Summary. Nevado del Ruiz is a broad, glacier-covered volcano in central Colombia that covers more than 200 km2. Three major edifices, composed of andesitic and dacitic lavas and andesitic pyroclastics, have been constructed since the beginning of the Pleistocene. The modern cone consists of a broad cluster of lava domes built within the caldera of an older edifice. The 1-km-wide, 240-m-deep Arenas crater occupies the summit. The prominent La Olleta pyroclastic cone located on the SW flank may also have been active in historical time. Steep headwalls of massive landslides cut the flanks. Melting of its summit icecap during historical eruptions, which date back to the 16th century, has resulted in devastating lahars, including one in 1985 that was South America's deadliest eruption.

Source: Servicio Geológico Colombiano (SGC)