Instituto Geofísico del Perú (IGP) reported moderate levels of activity at Sabancaya during 15-21 May with a daily average of 37 explosions. Gas-and-ash plumes rose as high as 2.4 km above the summit and drifted NE, E, and SE. Eight thermal anomalies originating from the lava dome in the summit crater were identified in satellite data. Seismic sensors detected 232 volcanic activity-related earthquakes, in addition to volcano-tectonic earthquakes. The Alert Level remained at Orange (the second highest level on a four-color scale) and the public were warned to stay outside of a 12-km radius.

Geological Summary. Sabancaya, located in the saddle NE of Ampato and SE of Hualca Hualca volcanoes, is the youngest of these volcanic centers and the only one to have erupted in historical time. The oldest of the three, Nevado Hualca Hualca, is of probable late-Pliocene to early Pleistocene age. The name Sabancaya (meaning "tongue of fire" in the Quechua language) first appeared in records in 1595 CE, suggesting activity prior to that date. Holocene activity has consisted of Plinian eruptions followed by emission of voluminous andesitic and dacitic lava flows, which form an extensive apron around the volcano on all sides but the south. Records of observed eruptions date back to 1750 CE.

Source: Instituto Geofísico del Perú (IGP)