What could happen if the Volcan de Colima eruption goes Plinian?

On Thursday 9th July 2015, Volcan de Colima (Volcano of Fire) in Mexico began erupting. Check out the webcam for live images!

Information is a little scarce at this stage, and some information is a little contradictory but the Denver Post has some nice images. Additionally, there are some nice images appearing on twitter.

The village of  Yerbabuena is estimated to have received about 5 cm of volcanic ash fall due to the eruption, and ash fall has reached as far as Colima City.

Many settlements are located around Volcan de Colima

There are three scenarios of how the situation could evolve:

  • A gradual waning of activity in coming weeks
  • A 1913-like explosion
  • A collapse of the volcano’s dome

Officials from Mexico’s civil protection authority have described the behaviour as atypical and not seen since the last major eruption over 100 years ago on January 18-24 1913. This has raised some concerns that the current activity could evolve into a more major eruption, or what volcanologists call a “Plinian eruption”. A plinian eruption is the biggest of all the eruption styles.

The 1913 eruption and what could happen if a Colima goes Plinian.

Pyroclastic flows

During the 1913 Plinian style eruption of Colima volcano, an eruption column rose to more than 20 km above the volcanoes crater. Eventually, due to the weight of the upper part of the column, the eruption column collapsed resulting in what is called a “pyroclastic flow”. A pyroclastic flow is a fast moving, extremely hot torrent of gas, volcanic ash, and blocks. The eruption of Volcan de Colima in 1913 resulted in the deaths of eight people. However in the last 100 years substantial population growth has occurred in the region. It has been estimated that a similar pyroclastic flow today could impact on about 15,000 people.

Pyroclastic flows are almost always deadly to those that they contact, and incredibly destructive to buildings. Additionally, due to the level of destruction and amount of volcanic material they bring with them they can cause the abandonment of settlements, as has happened to Plymouth, the capital city on the island of Montserrat due to the eruption of Soufriere Hills volcano. 

Lahars

Lahars are also a problem when rainfall interacts with unconsolidated materials that are erupted from volcanoes. It is currently the rainy season in the area, and so the threat to communities around the volcano from lahars could be large, even if the eruption does not become plinian.

Ash fall

Volcanic ash fall is the particles from the eruption column being dispersed largely by wind and falling to the ground. Volcanic ash can fall great distances from the source volcano. Although, it is not usually deadly, volcanic ash fall can be disruptive to everyday life due to impacts on:

In addition, it often must be cleaned up which can be extremely time consuming, expensive, and labour intensive.

A research article in 2010 by Rita Fonesca and Ana Lillian Martin Del Pozzo explained the potential elements exposed to volcanic ash if the 1913 eruption were to occur today. To summarise some of the findings:

  • It was estimated that the 1913 eruption resulted in wide spread volcanic ash which affected over 700,000 people. Again, due to population growth this number would be around 5 million today. Previous eruptions have resulted in volcanic ash fall in Mexico City, which today has a population of over 20 million.
  • Much of the population in the area works in the farming industry, and so the impact of a plinian style eruption on agriculture could be large. This would be problematic for the region as agriculture is important in both local and regional economies.
  • There are 14 international airports now located in the area that was impacted by the 1913 eruption. This would significantly impact air travel in the area as airport often must close due to volcanic ash in the air space or to clean-up fallen volcanic ash on the airport. This is because volcanic ash is extremely abrasive and can be very damaging to planes. In addition, when planes take off or land they can spread the volcanic ash to other areas.
  • There are a number of important highways in the areas which connect the region to major cities.

At this stage it is difficult to determine whether Volcan de Colima will indeed become Plinian, and so it is important that we recognise that it is not a certainty. However, given what the 1913 eruption could do today, it is important to recognise what could potentially occur to develop appropriate preparedness plans.

I will be watching Volcan de Colima’s development with great interest.

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