A powerful mid-afternoon eruption of the Turrialba volcano, currently the most active in Costa Rica, opened new vents in the crater, which suggests that a new caldera could form in the future.

According to geologists from the Observatory of Volcanology and Seismology of Costa Rica (Spanish acronym: OVSICORI), the eruption took place at 3:42 pm on a cloudy Friday afternoon as most people prepared to enjoy the three-day holiday weekend.

An interesting observation about this latest eruption is that it opened two new vents next to the main crater. The formation of these two vents can be seen in the video below; the surface cracks open at the moment the eruption is at its most powerful.

The volcanic activity of this colossus has been unfolding over the last two years, and it has previously resulted in the formation of a caldera and even a pretty, yet very toxic, turquoise lake inside the western crater.

The formation of the two new vents, which are smaller than fissure vents, suggests that the Turrialba volcano may be ready for a new caldera. The conditions are just right; after all, rainfall levels are on the rise and magma seems to be shifting gradually.

As explained by the Geology Department of San Diego State University in California:

When an erupting volcano empties a shallow-level magma chamber, the edifice of the volcano may collapse into the voided reservoir, thus forming a steep, bowl-shaped depression called a caldera (Spanish for kettle or cauldron). These features are highly variable in size, ranging from 1-100 km in diameter.

In most cases, they can be readily differentiated from summit craters, which are generally much smaller and form by explosive erosion of the central vent. Felsic calderas are surrounded by thick blankets of pumice derived from the eruption of voluminous pyroclastic sheet flows.

The Turrialba Volcano National Park is currently closed to visitors.