Sunday 24 October 2021

GAGXANUL, THE ACTIVE VOLCANO IN QUETZALTENANGO

Today, The Grandma has been following the latest news about La Palma, the Canarian Island, and Cumbre Vieja, the volcano that erupted last month, and it is still active destroying towns and changing landscapes.

The Grandma has remembered another volcano, Gagxanul, that erupted on a day like today in 1902 creating a situation very similar to La Palma's one.

Santa María Volcano is a large active volcano in the western highlands of Guatemala, in the Quetzaltenango Department near the city of Quetzaltenango.

The volcano was known as Gagxanul in the local K'iche' language, before the 16th century Spanish conquest of the region.

The VEI-6 eruption of Santa María Volcano in 1902 was one of the three largest eruptions of the 20th century, after the 1912 Novarupta and 1991 Mount Pinatubo eruptions. It is also one of the five biggest eruptions of the past 200, and most likely 300, years.

Santa María Volcano is part of the Sierra Madre range of volcanoes, which extends along the western edge of Guatemala, separated from the Pacific Ocean by a broad plain.

The volcanoes are formed by the subduction of the Cocos Plate under the Caribbean Plate, which led to the formation of the Central America Volcanic Arc.

Eruptions at Santa María are estimated to have begun about 103 ka. Construction of the volcanic edifice occurred in four phases, from 103-72, 72, 60-46, and 35-25 ka, building up the large cone that reaches about 1,400 metres above the plain on which the nearby city of Quetzaltenango sits. Following the cone-building eruptions, activity seems to have changed to a pattern of long periods of repose followed by the emission of small lava flows from vents on the mountain.

More information: The MET Museum

The first eruption of Santa María in recorded history occurred in October 1902. Before 1902 the volcano had been dormant for at least 500 years and possibly several thousand years, but its awakening was clearly indicated by a seismic swarm in the region starting in January 1902, which included a major earthquake in April 1902.

The eruption began on 24 October, and the largest explosions occurred over the following two days, ejecting an estimated 8 cubic kilometres of magma. The eruption was one of the largest of the 20th century, only slightly less in magnitude to that of Mount Pinatubo in 1991. The eruption had a Volcanic Explosivity Index (VEI) of 6, thus being Colossal.

The pumice formed in the climactic eruption fell over an area of about 273,000 square kilometres, and volcanic ash as far away as San Francisco, California, 4,000 kilometres away.

The eruption occurred out of a vent on the southwest side of the volcano, leaving a crater about 1 kilometre in diameter and about 300 metres deep, stretching from just below the summit to an elevation of about 2,300 metres. The first evidence of the eruption was a sprinkling of sand on Quezaltenango. The wind then changed from the south to the east and ashes began to fall at Helvetia, a coffee plantation 10 kilometres southwest.

Because of the lack of recorded eruptive activity at Santa María, local people did not recognize the preceding seismicity as warning signs of an eruption.  

Estimates are that 6,000 people died as a result of the eruption.

In the middle of the disaster, Quetzaltenango regional authorities had to take charge, as the central government was focused on the celebration of the Fiestas Minervalias, the largest propaganda festival of president Manuel Estrada Cabrera' regime; furthermore, the central government was so focused on the festival that it tried to minimize the impact of the eruption and went as far as tell the citizens that it was not in Guatemalan soil, but in México.

Furthermore, the official government response was to tell Quetzaltenango authorities that there were no funds for the recovery, as those were already spent to help after the April 1902 earthquake.

Under such circumstances, Quetzaltenango regional authorities declared that all the West zone agricultural harvest was ruined, and forecasted famine due to food shortages; likewise, cattle were dying and there were meat shortages as well. They were allowed by the central government to import flour free of taxes for the next few months.

For the native people the eruption consequences were catastrophic: they not only lost relatives, friends, homes and harvest, but they were also forced to work free of charge in the recovery while criollo landlords were compensated for the loss with lands that were confiscated from native communities in San Miguel Uspantán Quiché Department, Panam in Suchitepéquez Department and in Sololá Department.

More information: Geology

The 1902 eruption sequence of events:

-24 October. 5:00 pm: At San Felipe a sound was heard, similar to the roar of a waterfall, for five minutes, coming from the volcano; but the mist surrounding the volcano did not allow any direct observation of what was happening.

-24 October. 6:00 pm: Cinders and ashes started falling over Quetzaltenango.

-24 October. 7:00 pm: Witnesses recall seeing lightning and a strong fiery red light coming from the volcano, and noise similar to that of an industrial furnace.

-24 October. 8:00 pm: From San Felipe one could see a giant plume of black ash with numerous whirlwinds crossed by thousands of lightning bolts and curved lines of red light. All the area surrounding the volcano kept shaking, and large explosions could be heard as far as 160 km away; strong winds carried ash and debris as far as 800 km way, or even more; a part of the cloud hovered on the north side of the cone for days, and a pitch-black darkness ensued.

-25 October. 1:00 am: The eruption became more violent and large rocks from the volcano started falling as far as 14 km away, destroying towns and farm houses.

-26 October. 12:00 am: The volcano calmed down.

-26 October. 3:00 pm: Another eruption, but this time it was a white plume that came out, which was likely composed of water vapour.

More information: Volcano Top Trumps

The 1902 eruption was followed by 20 years of dormancy. New eruptions began in 1922, with the extrusion of a lava dome complex in the crater left by the 1902 eruption.

The lava dome complex, which was named Santiaguito, is still active today, with over 1 km3 of lava erupted so far. The lava dome complex has four main domes: El Caliente, La Mitad, El Monje and El Brujo. The currently active vent is El Caliente.

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. Lahars are particularly large and frequent during periods of high volcanism at Santiaguito.

The town of El Palmar, 10 kilometres 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.

More information: Smithsonian Institution-Global Volcanism Program

Near constant lava flows occur from Santiaguito, and can reach up to 4 km from the vent. Lava flow activity occurs in cycles, with the longest lava flows occurring during times of high volcanic activity. Much shorter lava flows occur during the longer periods of low volcanic activity. These lava flows flow only a short distance from the vent before collapsing.

The magma at Santiaguito is rich in silica and is thus highly viscous. The lava flows are slow moving and mostly cause property damage, although in the past catastrophic pyroclastic flows have been triggered from lava flows, which have extended several kilometres towards the west.

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. 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.

More information: Oregon State University


The paradox of volcanoes was that
they were symbols of destruction but also life.
Once the lava slows and cools,
it solidifies and then breaks down over time
to become soil -rich, fertile soil.

Matt Haig

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