Deadliest volcano in Western Hemisphere shows signs of increased activity

An eruption on November 13, 1985, caused the deaths of more than 25,000 people around the town of Armero. The Nevado del Ruiz is a stratovolcano, similar to Washington's Mount St. Helens.

BOGOTA, Colombia – Experts say a volcano responsible for causing one of the largest disasters in the Western Hemisphere is showing signs of increased activity, which has forced the Colombian government to issue evacuations in the potential impact zone.

The Nevado del Ruiz volcano sits about 80 miles west of Bogotá, and according to Colombia’s Geological Survey, an earthquake swarm has increased to levels not seen since a disastrous eruption in the 1980s killed at least 25,000 people.

Authorities have raised the alert level to orange – the second-highest on a four-stage scale.

A recent update posted by the Global Volcanism Program said on March 30 some 11,600 earthquakes were detected, and the movement of underground fluid was likely responsible for increased ash emissions.


An estimated 57,000 people live in municipalities close to the volcano, and the population has only increased since the Armero tragedy caught thousands off guard on November 13, 1985.

According to the U.S. Geological Survey, the last major eruption occurred during a time of major political discourse, and the nighttime event was obscured by a significant storm.

"Within minutes, 23,000 people - most of the town’s inhabitants - were killed, entombed within a concrete-like mixture of mud, vegetation, buildings, and everything else swept away by the lahars. Sadly, the lahars reached Armero approximately two hours after the eruption - plenty of time for the people to have evacuated to higher ground, had they been notified more quickly," the USGS recounted.


President Gustavo Petro has encouraged people in the potential impact zone to evacuate and has asked authorities to hasten their response.

"We have asked the Departmental Risk Councils to speed up the preventive evacuation of 2,500 families that are at high risk due to the contingency of Nevado del Ruiz," Petro said in a statement.

According to Colombian officials, there have been 18 orange alerts since 1985, with none leading to a major eruption.

Volcanologists compare the Nevado del Ruiz to Washington’s Mount St. Helens. Both volcanoes are capable of explosive eruptions and dangerous mudflows that swallow everything in their path.