The Servicio Geologico Colombiano (SGC) reported continuing eruptive activity at Puracé during 17-23 December. Seismicity was characterized by pulses of tremor, long-period signals indicating fluid movement, and periods of continuous tremor. The seismicity was located at depths of less than 2 km and was related to internal movement of gases as well as emissions. Low-magnitude earthquakes indicating rock fracturing were located beneath Puracé and Piocollo volcanoes, within 3 km of the craters, at depths of 1-3 km. Gas-and-ash emissions, 2-7 per day, were associated with some seismic signals and visible in webcam images rising 600-1,700 m above the summit and drifting NW, W, and SW. Significant sulfur dioxide emissions detected in satellite data dispersed within 250 m of the crater. Elevated temperatures in the crater area continued to be detected and were possibly associated with the emissions of hot gases. White gas-and-steam emissions, first observed on 18 November, continued to rise from the fissure on the inner N wall. Ashfall was reported in Cristales (NW) and in the area of the Puracé Indigenous Reserve Cabildo (NW) during 16-17 December and in Coconuco (12 km WNW) and in Chapa (28 km SW) of the municipality of Sotará (23 km W) during 17-18 December. A gas odor was reported in Chapa and ashfall was noted in the Río Negro sector and at the Paletará Indigenous Council House (16 km SW) during 18-19 December. The Alert Level remained at Orange (the second highest level on a four-color scale) and the public was warned to stay away from the crater.

Geological Summary. Puracé is an active andesitic volcano with a 600-m-diameter summit crater at the NW end of the Los Coconucos Volcanic Chain. This volcanic complex includes nine composite and five monogenetic volcanoes, extending from the Puracé crater more than 6 km SE to the summit of Pan de Azúcar stratovolcano. The dacitic massif which the complex is built on extends about 13 km NW-SE and 10 km NE-SW. Frequent small to moderate explosive eruptions reported since 1816 CE have modified the morphology of the summit crater, with the largest eruptions in 1849, 1869, and 1885.

Source: Servicio Geológico Colombiano (SGC)