Observatorio Vulcanológico y Sismológico de Popayán, Servicio Geologico Colombiano (SGC) reported that the number of both volcanic tremor (VT) and long-period (LP) seismic events at Puracé were stable during 7-13 May with only a slight increase in both the number and intensity of LP events on 9 May. The VT events had low magnitudes and were located at depths up to 4 km beneath the volcano and its E flank. The largest VT events were a M 1.8 recorded at 2351 on 7 May and at 2202 on 10 May. LP earthquakes were located in similar areas as the VT events, at depths less than 2 km. Earthquakes indicating magma movement were recorded during 7-9 May. Inclement weather sometimes prevented visual observations of emissions, though during the second part of the week diffuse fumarolic emissions from the crater and the crater rim were visible. Both carbon dioxide and sulfur dioxide emissions remained above baseline levels. The Alert Level remained at Orange (the second highest level on a four-color scale).

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)