IGP reported that on 24-25 August an increase in volcano-tectonic and long-period earthquakes, and during 23-25 August there was a slight increase in white to blueish white fumarolic emissions that rose 500-1500 m above the summit of Sabancaya. On 25 August during the night instruments detected a sequence of explosive events that lasted 82 seconds. On 26 August INGEMMET reported long-period, volcano-tectonic, and hybrid earthquakes. White to light gray plumes rose 100-1300 m above the summit drifting SE.

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.

Sources: Instituto Geológico Minero y Metalúrgico (INGEMMET), Instituto Geofísico del Perú (IGP)