Science

What are supervolcanoes?

In volcanology there is a scale that we call the volcanic explosiveness index (IEV-VEI), which is an indicator of the size and explosiveness of eruptions. It records the amount (volume) of material that a volcano expels and the height of the eruptive column. This scale has a gradation of 8, but it is logarithmic which means that an increase of 1 is an explosion 10 times more powerful.

More information

  • Strombolian, pyroclastic or colada: dictionary to understand the La Palma volcano
  • En Español: How does the eruption in La Palma compare with a supervolcano?

Supereruptions have an IEV of 8, that is , are the most explosive eruptions on the scale. Supervolcanoes emit huge deposits of material, more than 1000 cubic kilometers. But they are very rare eruptions, it is estimated that their frequency is more than 10. 000 years. For example, there are no supereruptions in the recent human historical record although there are in the geological record. That is, we are sure that there have been them because they have been studied from geological deposits.

One of the best known supereruptions is that of Yellowstone, which occurred in what is now one of the best known national parks in the United States. The so-called Yellowstone caldera that formed after an eruption approximately 640. years, measures 55 x 72 kilometres. It is a super boiler. In Chile, for example, there was also another supereruption that formed the Diamante caldera approximately 130. 000 years. These supervolcanoes typically occur in subduction zones, where eruptions are most explosive. That is something that does not happen in the Canary Islands because it is not in a subduction zone, but in a hotspot zone or hot spot.

There are no supereruptions in the log recent human history, although there are in the geological record

Although, for example, Teide-Pico Viejo has had eruptions more explosive than those of La Palma these days, the eruptions on this island or those on El Hierro are like the one we are seeing now, with IEV of 2 or 3, that is, mainly Strombolian.

We are not sure what exactly causes a supereruption. The hypothesis is that they have very large magmatic chambers that suddenly empty, chambers that are much larger than those of the rest of the volcanoes. it would cause climate change. It has been studied that eruptions with a higher IEV emit so much ash into the atmosphere that it prevents the sun’s rays from passing through, which generates climate changes at a global level. In addition, in the area where these supereruptions occur, they cause total devastation because the products associated with them are generally pyroclastic flows (PDCs) that destroy everything around.

The largest volcano in the Solar System is Mount Olympus on the planet Mars. In fact it is as large as the entire surface of Spain. However, despite its large size, it is not related to supereruptions. In this case, it is a shield volcano such as Kilauea or Mauna Loa in Hawaii, which are volcanoes with gentle slopes, which are formed by multiple consecutive eruptions with the emission of lavas, mainly from not very explosive eruptions. .

Laura Becerril Carretero is a doctor in Geology, expert in volcanology and professor and researcher at the Institute of Engineering Sciences, University of O’Higgins (Rancagua), Chile.

Question sent via email by Paula García Pásaro

Coordination and writing: Victoria Toro

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