Santa María Volcano

Santa María Volcano is a large active volcano in the Western Highlands of Guatemala, close to the city of Quetzaltenango. Prior to the Spanish Conquest it was called Gagxanul in the local K'iche' language.Its eruption in 1902 (VEI 6) was one of the four largest eruptions of the 20th century, after the 1912 Novarupta and 1991 Pinatubo eruptions. It is also one of the five biggest eruptions of the past 200 (and probably 300) years.

Santiaguito:
The 1902 eruption was followed by 20 years of dormancy. In 1922, new eruptions began, with the extrusion of a lava dome in the crater left by the 1902 eruption. The lava dome was dacitic in composition.These dome growth types are described by volcanologists as exogenous and endogenous respectively. Activity has been concentrated at several different vents, and Santiaguito now has the appearance of several overlapping domes.

The currently active vent is El Caliente.There are three other domes - El Brujo, El Mitad and El Monje.Although most of Santiaguito's eruptive activity has been relatively gentle, occasional larger explosions have occurred. In 1929, part of the dome collapsed, generating pyroclastic flows which killed anywhere from several hundred up to 5,000 people.Occasional rockfalls have generated smaller pyroclastic flows, and vertical eruptions of ash to heights of a few kilometres above the dome are common.

Volcanic hazards at Santa María:
The areas to the south of Santa María are considerably affected by volcanic activity at Santiaguito. Currently, the most common volcanic hazards at Santa María are lahars, which frequently occur in the rainy season due to heavy rainfall on loose volcanic deposits. The town of El Palmar, 10 kilometres (6 mi) from Santiaguito, has been destroyed twice by lahars from Santiaguito forcing the town to be moved to the present Nuevo El Palmar, and infrastructure such as roads and bridges have been repeatedly damaged.

Lahar deposits from Santiaguito have affected rivers all the way downstream to the Pacific Ocean.Lava flows do not occur frequently from Santiaguito, and tend to stretch no more than a few kilometres from the dome. The magma at Santiaguito is rich in silica and is thus highly viscous. Lava flows are therefore slow-moving and are of little danger to human life, although property damage may occur. Fast-moving pyroclastic flows can occur, and these may travel several kilometres from the dome.One hazard which could be devastating is the collapse of Santa María itself.

The 1902 crater has left the southern flank of the mountain above Santiaguito highly over-steepened, and a large earthquake or eruption from Santiaguito could trigger a huge landslide, which might cover up to 100 square kilometres (39 sq mi). However, this is thought to be unlikely in the short term.In light of the threat it poses to nearby populations, Santa María has been designated a Decade Volcano, identifying it as a target for particular study by volcanologists to mitigate any future natural disasters at the volcano.

Elevation: 3,772 m (12,375 ft)

Geology
Type: Stratovolcano
Volcanic arc/belt: Central America Volcanic Arc
Last eruption: 2012 (continuing)