(Bogota, Colombia) Temperatures inside the crater of the Nevado del Ruiz volcano in western Colombia continue to rise, as does seismic activity, a sign of a “very unstable” volcano and of a probable next eruption, Colombian authorities warned on Friday.

Nevado del Ruiz is remembered in Colombia for the tragedy of Armero, the second deadliest volcanic eruption of the 20th century, where some 25,000 people died in November 1985 in an avalanche of mud and ash caused by an eruption .

The ordeal of 13-year-old Omayra Sanchez, who died in a waterhole after three days of agony in front of the cameras, then shocked the whole world.

It has been on ‘orange’ alert since March 31, when the daily average of earthquakes inside the volcano rose from 50 to 12,000. A ‘red’ alert issued by authorities would mean a very severe eruption. nearby and an immediate large-scale evacuation of populations.

“The temperatures inside the crater have increased considerably, rising to more than 700 degrees Celsius,” presidential adviser Luis Fernando Velasco, in charge of the file, told local media.

Inside the volcano, which culminates at almost 5400 meters, “the magma is moving towards the crater”, breaking up the rocks and causing an increase in seismic activity, localized at a depth of 1 to 6 kilometers to the west and southwest of the crater.

In its latest volcano monitoring bulletin on Friday, the Colombian Geological Service (SGC) once again warns: “All indicators confirm […] that the activity of the Nevado del Ruiz volcano continues to be very unstable”.

The volcano has seen several small eruptions over the past ten years, but the SGC believes that “it is likely that within a few days or weeks it will have a major eruption”.

The latest images released by authorities show the mountain top lit up with glowing materials in the middle of the night from Thursday to Friday.

“Yesterday we saw a small eruption […] a combination of very hot ash and magma trying to get out of the crater,” Velasco said.

Some 57,000 people living in the 22 municipalities closest to the volcano are being evacuated in dribs and drabs, as farmers are reluctant to abandon their crops and livestock.

As in 1985, the main risk for the populations still remains an avalanche (or lahar), a mixture of ash, water and rocks, caused by the melting of the ice on the slopes of the volcano.

Located on the Central Cordillera and the Pacific Ring of Fire, Nevado del Ruiz is one of the 25 active volcanoes in Colombia.

In the south-east of neighboring Ecuador, the Sangay volcano expelled a column of ash eight kilometers high which fell on four surrounding provinces, said the Institute of Geophysics. The most affected was that of Chimborazo, 250 km from Quito, according to the Secretariat for Risk Management (SGR).

The activity of the colossus, which culminates at 5230 meters, but without a population living around it, has been considered between moderate and high since 2019.

“This emission is similar to that observed during the most active periods of the current eruptive period of the volcano,” said the Institute of Geophysics (IG).

The Sangay, located in the Amazonian province of Morona Santiago (on the Peruvian border), as well as the Cotopaxi and the Reventador, are among the volcanoes considered to be erupting in Ecuador, out of the 84 in the country.