Weekly activity report of the volcano Nevado del Ruiz, from 2 to 8 February 2016
The level of activity continue at level :
Activity level Amarillo or (III): changes in the behavior of volcanic activity.
Regarding the monitoring of the activity of the Nevado del Ruiz, the Colombian Geological Service reports that:
During the last week, the volcanic system continued to show unstable behavior. The recorded seismic activity is mainly associated with the fracturing of the rock in the volcanic structure. This type of seismicity was located mainly in the North and Northeast areas, and to a lesser extent, scattered in the North distals sectors, Southwest and North West of Arenas crater. Earthquakes depths during the week were between 0.7 and 8.1 km. Two increases in activity were highlighted during the 03 and 6 February.
The first increase was located in the Northeast area, at depths between 3.2 km and 6.4 km, with a maximum magnitude of 2.7 ML (local magnitude) at a depth of 5.3 km, corresponding to the earthquake on 3 February at 5:01 p.m. (local time). The second increase was located in the northern sector, at depths of between 4.3 km and 7.1 km, with a maximum magnitude of 3.6 ml (local magnitude) at a depth of 4.97 km, recorded at 20:39 (local time) on February 6. This event corresponds to earthquake of greater magnitude of the week and was reported as felt by the inhabitants of the area of influence of the volcanic edifice, as well as in the municipalities of Manizales and Villamaría (Caldas).
Seismic activity related to fluid dynamics inside volcanic conduits, was characterized by the occurrence of earthquakes long period (LP) and an episode of continuous tremor, recorded with a low energy level. These two signals are mainly located near the Arenas crater and in the South – Southeast sector of the volcano. These processes were accompanied by temperature anomalies, low to moderate, followed by satellite images provided by the system Mírová, from Italian universities of Turin and Florence. These thermal anomalies, on 03 and 07 February have been identified near the Arenas crater, confirming the instability of the volcanic structure.
The volcanic deformation measured from electronic inclinometers, global navigation satellite systems (GNSS) and satellite images, which record changes in the tilt, the position and shape of the volcano (respectively) during the last period evaluated recorded no change.
The volcano continues to emit into the atmosphere of significant amounts of water vapor and gases, including sulfur dioxide (SO2), as has been estimated by the permanent stations SCAN DOAS installed in the volcano area and satellite imagery.
The column of gas, steam and ash reached a height of 1500 meters above the summit of the volcano, on February 6. The direction of the dispersion of the column is in line with the prevailing wind in the area, which during the week showed a predominant direction towards the northwest over the volcano.
It is considered that the volcanic system continues to evolve. No new events that may indicate an acceleration of the process, involving greater instability of it requires the changes in activity level. While the instability of the volcano lasted for over five years, it is essential not to get used to a seemingly monotonous behavior of the volcano and monitoring official information that may be published by the Colombian Geological Service.
February 16 , 2016. Nevado Del Ruiz , Colombie :
Source : SGC.