On 7 November, INGEOMINAS raised the Alert Level for Nevado del Huila to Orange (on a 4-color scale where Orange is the second highest) due to increased seismicity and the probability of ash and gas emissions. During an overflight on 9 November, scientists observed continuous emissions of ash and gas from Pico Central, including from new areas to the S. Resultant plumes drifted SW and W, and ash deposits were seen on the summit. Fissures were evident on the S and SW parts of Pico Central. Evidence of ash and flowing water that originated from the SW fissure was possibly the cause of the Páez river turning grayish during the previous few days.
Based on analysis of satellite imagery and information from INGEOMINAS, the Washington VAAC reported that on 10 November a plume drifted W and WSW. Ashfall was noted in towns 20 km NW.
According to news articles, ash and sulfur dioxide plumes impacted local livestock, rural aqueducts, infrastructure, and rivers. On 11 November, about 20 families living near the Símbola River evacuated because of increased fumarolic activity.
Sources: Instituto Colombiano de Geología y Minería (INGEOMINAS), Washington Volcanic Ash Advisory Center (VAAC), El Pais, La Patria – “Reports provided courtesy of the Smithsonian’s Global Volcanism Program and the US Geological Survey’s Volcano Hazards Program.”