The Pacaya from the air.
The Pacaya rises about 30 kilometers south of the capital of Guatemala and is relatively easily accessible. It is a subduction zone volcano that produces a basaltic to intermediate melt. In addition to basalt, there are dacite (lava domes) and andesitic basalts.
The Pacaya is a young volcano. It was formed about 23,000 years ago on the edge of an older caldera in which Lake Amatitlan also lies.
The complex volcano is composed of several cones and domes and has several peaks. Of these, the Cerro Chino and the Cerro Grande were not active for a long time; the currently active crater cone is the McKenney. It was formed after the flank of an older cone collapsed 1100 years ago. This led to a large landslide, the deposits of which were found 25 kilometers from the Pacaya.
The eruptions of the PacayaIn historical times the Pacaya erupted at least 23 times. However, the volcano also remained dormant for more than a century, until in 1962, an area of the summit began to sink in; three years later, a dome grew up. Since then, the volcano is almost continuously active.
The activity of the Pacaya is various: It erupts predominantly strombolian and vulcanian. Short lava flows, small pyroclastic flows and debris avalanches are also part of its repertoire.
There were particularly active phases on the Pacaya between 1989 and 1991, and in January 2000 there was a phase of strong activity during which several villages were evacuated. In December 2008, the volcano generated four lava flows between 50 and 200 metres long; small strombolian eruptions came from a cone in the crater.
The most recent eruption took place on 28 May 2010. An ash cloud rose several thousand meters high and ash fell in the capital Guatemala City. A 7 cm thick ash layer was deposited. The airport was closed and a state of emergency was declared in some regions. Lava flows set vegetation at the foot of the volcano on fire. Only 2 days later the tropical cyclone "Agatha" swept over Central America and killed 150 people.
Since spring 2017 a new hornito grew in the McKenney crater, which over the months turned into an intracrater cone. It collapsed several times and then rebuilt itself. Strombolian eruptions were the architect of the cone. Mostly the tephra rose only 5-30 m high, but occasionally larger eruptions occurred. Lava flows flowed in southwestern direction.