Weekly activity bulletin of the volcano Nevado del Ruiz, from December 29, 2015 to January 4, 2016
Subject: internal activity level of the Nevado del Ruiz volcano.
The level of activity continues at:
level of activity Yellow or (III): changes in the behavior of volcanic activity.
Regarding the monitoring of the activity of the Nevado del Ruiz volcano, the Colombian Geological Service reports that:
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 earthquakes long period (LP), located mainly in the vicinity of Arenas crater and in the Southeast region of the volcano. The continuous tremor signal has introduced low energy levels and has remained constant since January 1, 2016. Do not rule out new episodes with high levels of energy of this signal, which is associated with gas and ash emissions in the atmosphere.
These processes were accompanied by thermal anomalies that can be followed using satellite images provided by different organizations, such as the portal Mírová from Italian universities of Turin and Florence. A thermal anomaly was observed on December 31, the highest level since access to these images, these abnormalities have been identified in the vicinity of Arenas crater, confirming the instability of the Nevado del Ruiz confirming that the volcanic processes continues to evolve.
As for seismic activity related to the fracturing of the rock in the volcanic structure, this type of seismicity was located mainly in the distal areas in North, South and Southeast compared to the Arenas crater and, to a lesser extent in the Arenas crater. The depths of earthquakes vary between 0.67 and 8.0 kilometers. The maximum magnitude recorded during the week was 1.6 ML (local magnitude), corresponding to an earthquake on January 1st at 10:39 p.m. (local time) at a depth of 5.84 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) in the last evaluated period, showed no significant changes.
The volcano continues to emit into the atmosphere large amounts of steam and water gas, including sulfur dioxide (SO2), as has been estimated by the SCAN DOAS permanent stations installed on the volcano zone and by 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 from the volcano toward the northwest.
It is considered that the volcanic system continues to evolve. No new event that may indicate an acceleration of the process, involving greater instability of it and consequently changes in the level of activity is recorded. It is essential to pay attention to official information to be published by the Colombian Geological Service.
January 07, 2016. Nevado Del Ruiz, Colombia :
Source : SGC.
Photos : SGC ( archives)