Observatorio Vulcanológico y Sismológico de Popayán, Servicio Geologico Colombiano (SGC), reported that during 13-19 September the number of earthquakes at Puracé was slightly higher compared to previous weeks. A seismic swarm was recorded on 15 September. Events were located about 1.5 km SW of Puracé crater, at depths of 3-4 km, and were as large as M 1.3. A total of 904 earthquakes were recorded during the week; 296 of those were volcano-tectonic events, 538 were long-period events, 54 were low-energy pulses of tremor, 11 were tornillo-type events, and five were hybrid events. Data from the GNSS (Global Navigation Satellite System) geodetic network indicated continuing inflation. White gas plumes were visible in the Anambío, Mina, Lavas Rojas, Cerro Sombrero, and Curiquinga webcams drifting NW. Sulfur dioxide emissions were as high as 2,021 tonnes per day. The Alert Level remained at Yellow (the second lowest on a four-color scale).

Geological Summary. Puracé in Colombia consists of an andesitic stratovolcano with a 500-m-wide summit crater constructed over a dacitic shield volcano. It lies at the NW end of a volcanic massif opposite Pan de Azúcar stratovolcano, 6 km SE. A NW-SE-trending group of seven cones and craters, Los Coconucos, lies between the two larger edifices. Frequent explosive eruptions in the 19th and 20th centuries have modified the morphology of the summit crater. The largest eruptions occurred in 1849, 1869, and 1885.

Source: Servicio Geológico Colombiano (SGC)