Explosive Eruption?

As we reach the end of the quest to find the cause of the collapse, I came across this blog post that posted an article by Richard Thornton, who talks about a study that places the blame on superheated volcanic gases and ash. Naturally I researched this further, but could not find the article mentioned. I did however find a similar article on the said Palenque Hydro-Archaeological Project. It is essentially a study of Palenque (as you may have guessed from the project name) – a large Maya city and the background of the blog- that has just been completed after 5 years, by the Foundation for the Advancement of Mesoamerican Studies (FAMSI). Located on the edge of the Chiapas Highlands, Palenque had a plentiful water supply, enabling it to become one of the most sophisticated and prosperous cities of the Maya region, yet inexplicably, it was one of the first to collapse. Palaeo-climate data provide very little evidence of a severe dry period that may have caused the abandonment of Palenque. Instead, a heavy layer of tephra (volcanic ash) dated for around 800 AD was found, along with evidence of destruction attributable to high heat.

Volcanic eruptions most certainly have the potential to ruin a society, causing massive causalities and property damage. The very recent awakening of the Popocatépetl volcano, near Mexico City, which prompted Richard Thornton to write his article, is a prime example. Several million lives could be lost if the volcano were to erupt, especially since last-minute evacuation of such a large metropolitan area is impossible.

There has been a long history of violent volcanic eruptions in Mexico, including that of Xocoteptl around 930 AD, in what is now northwest Mexico City. In fact, Mexico and the other Mesoamerican countries sit atop one of the most active geological zones in the world, containing numerous active and dormant volcanoes. For example, there is a chain of volcanoes (known to be active for the past two millennia) in the Chiapas state of Mexico and bordering Guatemala:

Location of El Chichon Volcano and surrounding cities.  The dotted line shows  the  areas most affected by the ashfall from the 1982 eruption. Source: Espindola et al. (2000)

The 1982 El Chichon volcanic eruption in this region was the worst known one in Mexico’s history, displacing over 20,000 people and causing at least 2,000 fatalities. This was partly due to the fact that people were not anticipating it, and so there was little time to escape once it had begun, and also because prior to the eruption it was not considered a hazardous volcano (De la Cruz-Reyna and Martin Del Pozzo, 2009). 

Before 1982: aerial photo of the summit of El Chichon volcano, Mexico

Post-1982 eruption: a kilometer-wide crater was formed, replacing the summit during the  most violent eruption in Mexico (known to humans) that killed 2,000 people and wiped out 9 villages.
Source: http://www.agiweb.org/geotimes/nov07/article.html?id=feature_danger.html

Espindola et al. (2000) suggested that such catastrophic eruptions may have been the prime mover of collapse of the Maya civilisation between 830 and 915 AD, after studies of past volcanic activity of El Chichon. They found that there have been at least 11 explosive eruptions in the past 8000 years, occurring around 550, 900, 1250, 1500, 1600, 1900, 2000, 2500, 3100, 3700 and 7700 years BP (note that the dates are rounded average calibrated radiometric age years). The 1250 BP eruption (i.e. centred around 676-788 AD) overlaps with the dates of the collapse of the western lowlands, including Palenque, which is located very close to the volcano (see map above). Had the Maya been unaware of the imminent danger of a volcanic eruption, the impacts would have been even more severe. Additionally, the impacts would not have been restricted to local areas due to the pyroclastic flows (a mix of ash, volcanic gases and lava) that would have reached distant sites, causing respiratory problems and potentially death. 


It seems volcanic eruptions may have been a primary cause for the collapse of Palenque, but I do not think it is possible to extrapolate this to explain the abandonment of the other cities. The small amount of literature on this particular subject is not sufficient enough for me to base a proper conclusion on, but for now I will discard this theory and begin to conclude the blog.