December 10 , 2015. EN. Etna , Nevado del Ruiz , Bromo .
December 10 , 2015.
Etna, Sicile :
Significant emissions of ash from the Northeast Crater, are emitted from the summit of Mount Etna. But it seems that now it is just a residual activity. It is possible that magma « retreat » in depth and that the volcano crumbling. This would be the reason of tremors that have arisen in recent days. If everything goes well, in time, we could see a cessation of the eruptive activity and a period of truce, at least until the magma begins again to recharge.
Update INGV Etna, December 09, 2015. 17h50
Eruptive activity is continuing at Etna with emission of grayish-brown ash from the Northeast Crater, which forms a plume trailing southeast (see the photo at left, by Boris Behncke of the INGV-Osservatorio Etneo, taken on the morning of 9 December 2015). These emissions, however, are not associated with any Strobolian activity or lava fountaining revealed by the visual and thermal observation systems. The pyroclastic material is blown by the wind toward the coast of the Ionian Sea.
The frequency and magnitude of events related to the seismic swarm on the northeast flank of Etna is currently diminishing significantly. This earthquake swarm is to be seen in a dynamic context characterized by pronounced deflation of the volcano as a consequence of the subtraction of a significant volume of magma, and represents the response of the tectonic structures in the eastern flank sector of the volcanic edifice.
Source : Gio Giusa. INGV .
Photo : Gio Giusa , Salvatore Lo Giudice.
Nevado del Ruiz , Colombie :
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 SERVICIO Geologico COLOMBIANO reports:
During the last week, the volcanic system continued to show an unstable behavior. The recorded seismic activity was mainly due to the fracturing of the rock in the volcanic structure. This type of seismicity has been located in areas: North, South, Southwest and in the Arenas crater at depths ranging between 1 and 5.2 km. The maximum magnitude recorded during the week was 1.7 ML (local magnitude), corresponding to an earthquake on December 2 at 00:50 (local time) near the Arenas crater at a depth of 2, 22 km.
Seismic activity associated with fluid dynamics in volcanic conduits, was characterized by recording type of LP earthquakes (long period) and episodes of volcanic tremor of short duration. Some of these events were associated with gas emissions and ash into the atmosphere, which could be verified by web cameras installed in the volcano area. Seismicity related to fluid circulation is located mainly in the Southeast sector and near the Arenas crater. The volcanic deformation measured from electronic inclinometers, navigation satellite systems (GNSS) and satellite images, which records changes in tilt, position and shape of the volcano (respectively) during the last period evaluated , did not show any major change.
The volcano continues to emit into the atmosphere of significant amounts of water vapor and gases, including sulfur dioxide (SO2). The column of gas, steam and ash reached a height of 900 meters above the summit of the volcano on 06 and 07 December . The direction of the dispersion of the column was in harmony with the wind regime, which during the week showed a predominant direction toward the northwest.
Although so far there has been no new episodes of signals called « drums« , associated with the rise of magma to the surface, it is considered that the system continues to evolve. New events can indicate an acceleration of the process, involve greater system instability and forces to alter the level of activity. It is essential to pay attention to official information to be published by the Colombian Geological Service. Therefore, we reiterate to the authorities in the departments of Caldas and Tolima the necessity of extreme vigilance, carried on the processes of reduction and vulnerability management and risk management activity of the Nevado del Ruiz volcano.
Source : SGC.Gov.Co
Bromo, Caldeira du Tengger , Indonésie:
Elevation 2329 m
PVMBG reported that during 15 November-4 December white plumes from Tengger Caldera’s Bromo cone rose as high as 150 m above the crater, and an intense sulfur dioxide odor was noted at the Bromo observation post. On 15, 23, and 27 November dense ash plumes rose 150 m above the crater rim. RSAM values increased at the beginning of November, and then sharply increased in the beginning of December. Based on seismic analysis, visual observations, and hazard potential, the Alert Level was raised to 3 (on a scale of 1-4) on 4 December. Residents and visitors were warned not to approach the crater within a radius of 2.5 km.
Based on information from PVMBG and satellite images, the Darwin VAAC reported that during 5 and 7-8 December ash plumes rose to an altitude of 3 km (10,000 ft) a.s.l. and drifted 55-185 km W, SW, S, and SE.
Sources: Pusat Vulkanologi dan Mitigasi Bencana Geologi , Centre d’avis de cendres volcaniques de Darwin (VAAC)
Photo : Øystein Lund Andersen