November 26, 2015. EN. Nevado Del Ruiz, Sakurajima, Telica.

Home / blog georges Vitton / November 26, 2015. EN. Nevado Del Ruiz, Sakurajima, Telica.

November 26, 2015. EN. Nevado Del Ruiz, Sakurajima, Telica.

November 26, 2015.

 

 

Nevado Del Ruiz, Colombia :

Subject: internal activity level of the Nevado del Ruiz volcano.

Yellow activity level 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 through the OBSERVATORIO VULCANOLÓGICO Y SISMOLÓGICO OF MANIZALES, reports that:

During the last week, the volcanic system continued to show unstable behavior. The recorded seismic activity was mainly due to the fracturing of the rock in the volcanic structure. This type of seismicity was located in the North-East areas and South-east of the volcano, in the Arenas crater, and to a lesser extent in the Northwest sectors and southwest of the volcanic structure at depths between 0.5 km and 7.8 km. The maximum magnitude recorded during the week was 2.6 ML (local magnitude), corresponding to an earthquake on November 20 at 09:58 (local time), located in the eastern sector of the Arenas crater at depth of 2.8 kilometers.

 

Seismic activity associated with fluid dynamics in volcanic conduits, was characterized by record of LP type earthquakes (long period) and episodes of volcanic tremor of short duration, not associated with emissions of ash in the atmosphere. The volcanic deformation measured from electronic inclinometers, global navigation satellite stations (GNSS) and satellite images, which record changes in tilt, position and shape of the volcano (respectively) during the last period evaluated, showed no major change.

The volcano continues to emit into the atmosphere of significant amounts of water vapor and gases, including sulfur dioxide (SO2). The gas and steam column reached a height of 2000 meters above the volcano’s summit on November 17. 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.

nevado

In recent months, very quietly, there have been several shorts episodes of fracture seismic events characterized by low energy, that occur at regular time intervals with waveforms and similar energy. Technically these signals are known as « drum » or « drum roll » for their meaning in Spanish. The most important of these signals episodes was reported by extraordinary bulletin on August 20, 2015. They correspond more recently to 13 events recorded in November, characterized by a much lower energy level. The presence of these seismic events has been associated on other volcanoes, when the magma rise to the surface and his implementation in the form of lava domes. To verify the existence of morphological changes in the Arenas crater of the volcano Nevado del Ruiz, associated with these « drums«  signals during the last week, two overflights were carried out with the support of the Colombian Air Force (FAC) and USAID / OFDA. However the weather in the volcano area and in particular high density and volume of the gas and vapor column has prevented the observation of the crater. Overflights of the Colombian Geological Service continued to manage the increased monitoring of surface activity and to verify the changes.

 

While so far the seismic events mentioned above are considered as very low energy and associated with the rise of small volumes of magmatic material, the volcano remains at yellow activity. It is important to note that the system continues to evolve and no new events can indicate an acceleration of the process, involving greater system instability. The changes, therefore, of the level of activity is rejected. It is essential to pay attention to official information to be published by the Colombian Geological Service.

Source : SGC.

 

Sakurajima, Japan :

Mount Sakurajima alert level lowered as volcanic activity diminishes.

The Meteorological Agency on Wednesday downgraded its warning level for Kagoshima Prefecture’s Mount Sakurajima, citing diminished volcanic activity.

With no major eruptions observed since Sept. 17, the agency lowered the alert level for the 1,117-meter volcano in Kagoshima Prefecture on the 5-point scale from 3, which warned people not to get close to the volcano, to 2, which advises them not to approach the crater.
The alert level was raised from 2 in October 2010 and had stayed above that level since then.

 

sakurajima

Despite the downgrade, the city of Kagoshima said it will continue to restrict access to within a 2-kilometer radius of Sakurajima’s Showa and Minamidake summit vents.

The volcano is located just 4 km away from the city center and some 50 km from the Sendai nuclear power plant that was restarted in August.
With increased earthquakes and small eruptions originating from the volcano following rapid crustal movements, the agency raised the alert level from 3 to 4 on Aug. 15, the highest ever for Sakurajima. The authorities instructed nearby residents to prepare to evacuate.
But on Sept. 1, it downgraded the level to 3 again, saying the risk of a large-scale eruption had diminished.

With no significant eruptions observed since Sept. 17, the volcano saw the second-longest period without any blasts since the Showa crater became active again in 2006.
Sakurajima experienced a major eruption in August 2013, spewing ash some 5,000 meters into the sky.

Source : japantimes

Photo :  S.Nakano.( 2010)

 

 

Telica, Nicaragua :


Yesterday in the morning, the Telica volcano showed a new explosive phase, which started at 8:47 with gas explosions, ash and rocks, produced by the accumulated pressure in the volcano’s crater floor, which had been blocked.
Are recorded in total up to 05 explosions, including two strong explosions at 8:47 and 8:48 in the morning, accompanied by gas emissions and emission of ash that reached a height of 2 kilometers.
The emission of ash lasted about 35 minutes.

 

 

Furthermore, the expulsion of rock fragments of different sizes was recorded up to 900 meters from the crater.
According to the civil defense report ash falls were reported in municipalities and communities
of Quezalguaque, Posoltega, Chichigalpa,
Cristo Rey, Los Sanjones, Los Pellizcos, Chinandega, Punta Caliente, San Lucas, El higueral, La Grecias and El Viejo.

 

 

On November 25, 2015, six explosions were recorded on the Telica volcano, according to INETER. The largest took place in 6:04 and 8:30. They were accompanied by ash plumes and gas affecting the south of the volcano, particularly the town of Los Portillos.
Currently, the seismicity of Telica volcano  maintains a low gas output, moderate, the RSAM values are within normal parameters, and therefore, at this time do not represent any danger for the population.

Source : INETER.

Photo : Ineter, Jorge Arias.

 

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