The Nevado del Ruiz volcano does not seem to want to give truce to the inhabitants of the area. On Thursday, new earth movements reminded those present that the threat of the volcano is still present.
New seismic activity. The Colombian Geological Service (SGC) has reported new earthquakes in the area of influence of the Nevado del Ruiz Volcano and its surroundings. The most significant occurred yesterday Thursday at 3:14 p.m. local time (10:14 p.m. CEST), with a magnitude of 2.2 and whose epicenter was at a depth of about 5 kilometers under Casabianca (Tolima).
To this can be added two earthquakes that occurred in surrounding valleys. First occurred in Armero (Guayabal) at 11:13, local time (18:13 CEST), magnitude The second occurred in Valle del Cauca at 2:09 p.m. local time (21:09 CEST), of magnitude 3.5.
The last 24 hours have been seismically active in the Latin American country beyond the surroundings of Nevado del Ruis. The last and most intense of the earthquakes was reported this morning (at 1:05 local time; 08:05 CEST) in the Chiles Volcanic Complex, on the border with Ecuador, with a magnitude of 3.8.
Orange alert continues. Therefore, it does not seem that there will be an improvement in the situation of the volcano in the coming days. The authorities maintain the orange level of activity (which equates to a “probable eruption in a term of days or weeks”).
In the last extraordinary bulletin of the SGC (issued on Thursday the 4th before the latest movements) the agency talks about a seismic activity linked to the movement of fluids inside the volcanic conduits. These earth movements would also be linked to “pulsatile ash emissions.”
Regarding the emissions from the volcano, it is also explained that the degassing of sulfur dioxide continues, as well as the output of water vapor. The column of gases and ash reaches an altitude of approximately 1.4 kilometers.
To install Los lahares. A term that has gained some notoriety in recent weeks, lahars are mudflows or avalanches. As the SGC clarified in a statement, the “primary lahars” (its technical name) arise due to “[del] rapid melting of the ice and snow from the glaciers that cover the volcanic edifice, due to the incandescent material that comes out of the volcano at the time of the eruption”.
These types of avalanches imply a significant risk due to the high speeds they reach and the amount of material they can drag. Proof of this is the tragedy of Armero, caused by the eruption of Nevado del Ruiz in 1985. With 25,000 deaths, the memory of the event still shocks the locals.
Primary wineries must be distinguished from secondary ones. The latter occur “when unconsolidated (loose) volcanic material, deposited in certain places by previous eruptions, is remobilized by rain,” explains the SGC. These events are generally less intense than the primary ones and the volume of their discharge depends on the intensity of the rains.
Eight years in the making. Since the volcano began its eruptive process in 2014, Nevado del Ruiz has been kept under the watchful eye of Colombian geologists due to the risk involved. The increase in the intensity of this process began in October of last year, but it was already at the end of March of this year that the experts changed the alert status from yellow to orange.
Located between the departments of Tolima and Caldas, Nevado del Ruiz is a stratovolcano (that is, its structure is made up of numerous geological strata). The volcano rises to 5,321 meters above sea level, which makes it visible even from Bogotá if the weather allows it.
It also has an active crater that exceeds 800 meters, although the diameter of this geological formation reaches 15 kilometers. It is estimated that, as a volcano, it dates from the Pliocene, about 1.8 million years ago and owes its name to the glacier that crowns it and whose volume reaches a whopping 1.2 cubic kilometers.
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Image | Luis Alejandro Bernal Romero, CC BY-SA 2.0