It was the best of times, it was the worst of times. It certainly was volcanic times. This is the story of three great cities, one lost in the mist of time, one almost gone into the mist of time, and one that is a buzzing metropolis, doomed to disappear into the tephric mist of a time to come.
Welcome to the Capitals of Guatemala.
Even though Técpan was the first military center for the Spanish invaders it is Ciudad Vieja that was the first real place of government in the colonial era Guatemala. Even more correct would be to say that the first capital of what is now known as Guatemala was the Cakquikel city of Iximché, but let us leave that behind us for now. It was Ciudad Vieja that is interesting for this Tale of Three Cities.
The city was founded in 1527, and had a rather short lifespan. In 1541 Agua suffered a dramatic collapse causing a lahar that totally ruined the city forcing the inhabitants to permanently evacuate the city. For two years Guatemala was without a capital.
Because of the flooding water and the lahar devastating Ciudad Vieja the volcano was renamed into Volcan de Agua. At the same time they renamed the nearby volcano into Volcan de Fuego. Nobody knows what devastated the sides of Volcan de Agua. Most likely it was earthquake activity during a magmatic emplacement at depth, but that is just a theory. What is though known is that the side of the crater gave way, and the crater lake came crashing down picking up any loose items on the way.
Volcan de Agua is a youthful young stratovolcano with no known historical eruptions. It is though showing low level signs of activity. It is today judged to be dormant, but in a state that can change at any time.
In 1543 the new capital was formed in the next valley. It was named Santiago de los Caballeros. It was probably one of the least fortuitous places to have a capital in. Not only is Volcan de Agua less then 5km from the city, there is also the highly active Volcan de Fuego close to the city. To top it off the city also had to contend with Acatenango. During its history (1543 – 1776) it was inundated under tephras from Volcan de Fuego no less than 23 times, and two of those eruptions were VEI-4 category.
To really make things interesting it is placed on top of an active fault line.
On the 29th of September 1717 much of Santiago de los Caballeros was destroyed in a large earthquake. More than 3000 building were ruined and the Spanish Crown started to contemplate moving the city. Sadly they contemplated to long.
On the 29th of July 1773 the Santa Marta Earthquake struck the city with a force estimated to be 7.5 on the magnitude scale. Most of the city was left in burning ruins after the earthquake. Equally devastating was the intensive swarm of unusually powerful aftershocks that hammered the city into December the same year. In 1776 the Spanish Crown finally had it and decided to move the capital to a new safer spot. The new city was named after both the region and the country for good luck. Now we know that the move was from the ashes into the fire, quite literally. But we will get back to Guatemala City in the next installment.
Left were the ruins of the old capital, now renamed into Antigua Guatemala, basking in the shade of its large volcanoes.
Acatenango & Volcan de Fuego Massif
Acatenango and Fuego are joined to the hip quite literally. It seems like they do not share the same magmatic system, even though some researchers have extemporized that the magmatic system of Fuego runs through the magmatic system of Acatenango. The reason for this theory is to explain that some of the eruptions of Fuego carry magmatic signatures from Acatenango, but Acatenango never have the magmatic signature of the bulk of Fuegos eruptions. Be that as it may, the two volcanoes have rather different patterns regarding their eruptions.
Acatenango has had very few historical eruptions. The last real eruption cycle began on the 18th of December 1924 with a set of large phreatic detonations; this was later followed by a central vent eruption and a radial fissure eruption from the Pico Central crater. During this eruption the volcano ejected the telltale amphibole bearing dacite that is the most common lava emanating from Acatenango. The eruption ended on the 7th of June 1925 and was rated a VEI-3. In August 1926 the volcano sprang back into life with a new set of phreatic detonations followed by renewed lava ejection from the north flank of Pico Central. The eruption ended on the 19th of May 1927 and was rated a VEI-2.
On the 12th of November 1972 a set of phreatic detonations started that lasted for about a month. No lava was ejected so it is seen as an aborted eruption. The phreatic detonations was powerful enough to gut the Yepocapa saddle of the Pico Central cone.
Historically Acatenango has not suffered from frequent eruptions. Instead the eruptions have tended towards being larger than the eruptions of its twin Fuego. The greatest risks are the well documented deep layers left from large scale pyroclastic flows. The flow fields from the 370 BC eruption would have eradicated any of the adjacent towns and villages in an instant. Therefore the authorities would be well advised to prepare proper evacuation maps of all the possible routes pyroclastic flows can take from Acatenango and put in place large scale evacuations in case Acatenango rumbles back in to life.
Volcan de Fuego was born out of the scrap heap left by the massive Meseta volcano when it went lumbering towards the ocean in the Asquintla debris avalanche. Fuego is one of the two most prolific volcanoes in Guatemala. One could almost say that it is erupting more often than it is resting.
Normally it has small to moderate sized eruptions with an average of VEI-2. But it quite often has short-spanned VEI-3 eruptions that are more of a bother for the locals. Two VEI-4 eruptions are documented, the last in 1974 when it had numerous pyroclastic flows killing residents in nearby villages.
Fuego shows a varied pattern of behavior ranging from lahars and pyroclastic flows (the killers), via lava bombs and lava flows from central vents and fissures to spine growths and exploding extruded domes. These varied behaviors make Fuego into a fairly unpredictable volcano. What is lacking is good mitigation with pre-prepared evacuation maps from the valleys most affected by pyroclastic flows and lahars. Also the will to evacuate and being evacuated is slightly low locally, something that can be understood if one think about that the people in the villages are really poor without the means to support themselves if they evacuate.
If you think this was bad choice for cities, just wait until the next installment of A Tale of Three Cities.
P.S. Do not miss the expert comments at the end of the comments section. D.S.