Weekly Bulletin of Activity of the volcano Nevado del Ruiz, from 22 to 28 December, 2015
Subject: internal activity of the Nevado del Ruiz volcano.
The level of activity continues at : activity level Yellow or (III): changes in the behavior of volcanic activity.
Regarding the monitoring of the activity of the Nevado del Ruiz volcano, the SERVICIO Geologico COLOMBIANO reports:
During the last week, the volcanic system continued to show unstable behavior. The recorded seismic activity was mainly associated with fluid dynamics in volcanic conduits. This type of seismicity, was characterized by the appearance of continuous tremors and type of long period earthquakes (LP), located mainly in the vicinity of Arenas crater and in the Southeast region of the volcano. Two episodes of continuous volcanic tremors recorded between 20 and 25 December 2015 whose presence was reported by extraordinary bulletin had a lower power level since the same evening until morning, indicating variability the volcanic system. Do not rule out that he could present new episodes of this signal, which is associated with the emission of gases and ash in the atmosphere, which can be dispersed in accordance with the system of winds blowing in the region.
As for seismic activity related to the fracturing of the rock in the volcanic structure, this type of seismicity was located mainly in North-distal zones, Southwest, South and South-East of the Arenas crater and, a lesser extent around the crater. The depth of the earthquake was between 1,05 and 7,66 kilometers. The maximum magnitude recorded during the week was 1.4 ML (local magnitude), corresponding to an earthquake on December 28 at 14h57 (local time) 7 km north of Arenas crater at a depth of 5, 39 km.
The volcanic deformation measured from electronic inclinometers, global navigation satellite systems (GNSS) and satellite images, which record changes in tilt, position and shape of the volcano (respectively) during the last period evaluated, did not show significant changes.
The volcano continues to emit into the atmosphere large quantities of steam of water and gas, including sulfur dioxide (SO2) which is characterized, as has been estimated by the permanent stations SCAN DOAS installed on the area the volcano and satellite imagery.
The column of gas, steam and ash reached a height of 1700 meters above the summit of the volcano on December 28. The direction of the dispersion of the column is in line with the regime of prevailing winds in the region, who, during the week showed a predominant direction toward the northwest over the volcano.
With satellite images for monitoring provided by the Italian universities of Turin and Florence (portal Mírová) and the University of Hawaii (MODVOLC) thermal anomalies were recorded on the volcano on 22, 23, 24 and 26 December .
It is considered that the volcanic system continues to evolve and new events may indicate an acceleration of the process. By involving greater instability thereof, changes in activity level may occur. It is essential to pay attention to official information to be published by the SERVICIO Geologico COLOMBIANO.
January 02, 2015. Nevado Del Ruiz, Colombia :
Source : SGC