THE RESTLESS SABANCAYA.

Sabancaya is an active 5,976m/19,606ft conical volcano built up by many layers of hardened lava, pyroclasts, pumice, and volcanic ash, in the Andes of Southern Peru. It is the most active volcano in Peru and is part of a 20km/12mi North-South chain of 3 major volcanoes, including the extinct and eroded 6,025m/19,767ft volcano Hualca-Hualca at the Northern end, the dormant 6,288m/20,630ft volcano Ampato to the South, and Sabancaya in the middle.
Sabancaya hosts several glaciers which cover an area of about 3.5 sq km/1.4 sq mi and descend as low as 5,400m/17,700ft on its flanks.
The andesite volcano of Sabancaya has been very active during historic times, with the earliest recorded eruptions in 1695 and 1758. The andesite is an extrusive (inside out) igneous, volcanic rock and considered the intermediate type between basalt and dacite. Magnetite, zircon, apatite, ilmenite, biotite, and garnet are common accessory minerals. It can be considered as the extrusive equivalent of plutonic diorite. Characteristic at convergent boundaries of tectonic plates where one plate moves under another and is forced or sinks due to gravity into the mantle, andesite represents the dominant rock type in island arcs like the Caribbean Islands. The average composition of the continental crust is andesitic. Along with basalts they are a major component of the Martian crust. The name "andesite" is derived from the Andes Mountain Range.
Following over 200 years of dormancy, satellites detected an increase in thermal emission in July 1986 and intense activity resumed in December of that year.
The most sustained period of activity began with explosive eruptions on May 28, 1990, and continued over 8 years. At the height of the activity in 1994, eruptions producing large ash clouds occurred every 2 hours. It is suspected that the cone may have grown to over 6,000m / 20,000 ft during that time.
Sabancaya is considered one of the most hazardous volcanoes in Peru, along with the massive Coropuna (Arequipa) and the cone of The Misti (Arequipa). Potential hazards include mud and pyroclastic flows down the Majes, Colca, and Siguas river drainages. During the 1988 eruption, cattle died in nearby areas either directly from poisonous volcanic gases or from eating contaminated vegetation.
Sabancaya is not the only restless Andean volcano in Peru and right now it has been restless for the last 2 years, with periods of heightened activity and return to quiet. It looks like the volcano has entered a new phase of activity, producing dozens of explosive eruptions since the last November, 2016.
The first explosion generated a 3.6 earthquake and a vigorous dark grey ash plumes that have been some of the highest ever recorded. Deformation of the volcano continues, which supports the idea that magma is still rising into the edifice and sulfur dioxide emissions remain high. An state of emergency that lasted 60 days was declared across 23 districts around Sabancaya due to this ash hazard.
Sabancaya right now still remain on Yellow alert status.