Disasters & Accidents

Seismic activity at Colombia’s Nevado del Ruiz volcano lessens

Bogota, Apr 9 (EFE).- Seismic activity within the Nevado del Ruiz volcano in central Colombia has dropped off in recent hours on the weekend and the column of gases being emitted from its crater has lessened, although that has not motivated Colombian authorities to reduce the orange alert declared in the zone on March 31, the country’s Geological Service (SGC) reported.

“Yesterday, April 8, 1,400 events were registered reaching a maximum magnitude of 2.4 ML (local magnitude), corresponding to the earthquake at 10:19 am,” said the SGC in its daily bulletin regarding the volcano’s seismic activity.

According to the report, as of 9 am on Sunday “about 180 events have been registered,” a significantly lower number than the 12,000 tremors registered over the past 10 days, an average of 1,200 per day.

“This marked decrease in the seismicity has coincided with a decrease in the size and thickness of the column of gases, particularly in terms of the water vapor content … so far this morning,” the bulletin added.

Due to this decreased activity, the SGC said that starting Monday “the number of daily seismic events will not continue to be reported, given that it is no longer as relevant parameter in the development of this activity as it was at the beginning.”

However, the agency added, parameters such as the location of the seismic events vis-a-vis the crater and their depth do take on greater importance in this kind of activity.

“The maximum altitude of the observed gas and/or ash column was 1,700 meters (5,576 feet), measured from the peak of the volcano with a direction of dispersion oscillating between east and southeast,” and the emission of sulfur dioxide into the atmosphere is being maintained at similar levels to those observed in previous days, the agency said.

The SGC warned that the volcano’s activity could fluctuate and, for a time, diminish with respect to earlier days, without that meaning that Nevado del Ruiz is returning to its prior minor level of activity, and thus the orange alert is being kept in place for the time being.

An eruption of Nevada del Ruiz, followed by the partial melting of the glaciers on it, on Nov. 13, 1985, caused an avalanche and mudslide that erased the town of Armero, killing more than 23,000 of the 25,000 residents there in Colombia’s worst recorded natural catastrophe.

EFE –/bp

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