Alert Level Increased at Two Chilean Volcanoes

Two of Chile’s volcanoes were raised from green alert to yellow alert following signs of unrest over the past week. Monitoring efforts will now be stepped up to diagnose the cause of the unrest and decide if further alert increases are necessary.

Copahue volcano borders the Biobío region of Chile and the Neuquén region of Argentina and last experienced a significant eruption in 2012 forcing residents nearby to evacuate. The volcano is classified as one of the highest risk in Argentina, but, interestingly, it is only 18th on Chile’s volcano risk list.

This is partly due to the proximity of settlements and also the unfortunate fact, for Argentinians, that the wind normally blows ash to the east and into Argentina. The change in alert from green to yellow was deemed necessary by SERNAGEOMIN since the volcano started producing gas emissions and small explosions near the crater region above the normal activity of the volcano.

Laguna del Maule

The other volcano that was switched from green to yellow alert is the Laguna del Maule volcanic complex. Laguna del Maule is not like the other archetypal stratovolcanoes that are easily observed all throughout Chile. Instead, the menace of this volcano is hidden beneath a tranquil lake. This is typical of caldera type volcanoes – their surface expression is often lower than the surrounding topography (mountains). However, caldera volcanoes also pack the most punch in terms of eruption size, and so they are treated with great caution.

Since June 11 OVDAS (the Southern Andes volcano monitoring center) started monitoring an abnormal increase in a type of seismic activity known as volcano-tectonic earthquakes (or VT events). This type of seismicity is commonly associated with the breaking of rock at depth and although a firm diagnosis of the cause at Laguna del Maule is not known, it can be speculated that the events indicate the movement of either magma or hydrothermal (hot) fluids.

For the past decades, scientists have been trying to understand an unusually high deformation rate at the volcano, meaning that the ground has been rising a lot (several tens of centimeters) and abnormally rapidly. Such signals are often associated with the growth of a magma body in the Earth’s crust.

The yellow alert level declared at both volcanoes is the second in a four tier system with orange and red the next highest levels. Laguna del Maule has never reached the highest level and thankfully so since it is capable of producing very large eruptions.

Copahue, on the other hand, experiences moderate eruptions relatively frequently and so was at the highest level red in 2012 and again in 2016 for a series of smaller eruptions. 

Two other volcanoes in Chile have been at yellow alert for several months, Volcán Villarrica and Nevados de Chillán.

New Explosion At Nevados De Chillán Volcano

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