January 06 , 2017. EN. Descabezado Grande , Sangay , Tungurahua , Cayambe , Cotopaxi , Bogoslof .

Home / Alaska / January 06 , 2017. EN. Descabezado Grande , Sangay , Tungurahua , Cayambe , Cotopaxi , Bogoslof .

January 06 , 2017. EN. Descabezado Grande , Sangay , Tungurahua , Cayambe , Cotopaxi , Bogoslof .

January 06 , 2017.


Descabezado Grande , Chile :

Special volcanic activity report (REAV)
Area Maule.
05 January 2017. 20h40 (local time).

The National Geological and Mining Service (SERNAGEOMIN) discloses the following information obtained by the National Observatory of the Volcanic Monitoring Network, processed and analyzed at the Southern Andes Volcanological Observatory, interpretation data center of the SERNAGEOMIN:
Thursday, January 5, 2017 at 07:54 local time (10:54 GMT), the monitoring stations installed near the Descabezado Grande volcano recorded one (1) earthquake associated with rock fracturing (volcano-tectonic). This event was located in the area of the main crater.
The location was obtained as follows

TIME OF ORIGIN: 07h54 hl (gmt-3)
LATITUDE: 35 ° 35’15.0 « South
LENGTH: 70 ° 45’26.4 « West
DEPTH: 3.7 km

After the main event was recorded a replica of lower magnitude. At the time of publication of this report, there is no information from authorities or communities in general on perceptions of the nearby event.
The level of technical volcanic alert remains at GREEN.
SERNAGEOMIN continues to monitor secure online, and will report in a timely manner on changes in volcanic activity in the region.


Descabezado Grande

Volcán Descabezado Grande is a late-Pleistocene to Holocene andesitic-to-rhyodacitic stratovolcano with a 1.4-km-wide ice-filled summit crater. Along with Cerro Azul, only 7 km to the S, Descabezado Grande lies at the center of a 20 x 30 km volcanic field. A lateral crater, which formed on the upper NNE flank in 1932 shortly after the end of the major 1932 eruption from nearby Quizapu volcano on the N flank of Cerro Azul, was the site of the only historical eruption. The Holocene Alto de las Mulas fissure on the lower NW flank produced young rhyodacitic lava flows. Numerous small late-Pleistocene to Holocene volcanic centers are located N of the volcano. The northernmost of these, Lengua de Vulcano (or Mondaca), produced a very youthful rhyodacitic lava flow that dammed the Río Lentué.

Source : Sernageomin.

Photo : andeshandbook.org


Sangay , Tungurahua , Cayambe , Cotopaxi , Ecuador :

Summary of observations made during the flight of survey of the Sangay , Tungurahua, Cotopaxi and Cayambe volcanoes.

On 21 and 23 December 2016, the technical staff of the volcanology department of the Geophysical Institute of the National Polytechnic School (IGEPN) made two flyovers of the active volcanoes of Ecuador. On December 21st in a Cessna 206 Stationair to the Sangay and Tungurahua volcanoes and on December 23rd in a KODIAK QUEST to the Cayambe and Cotopaxi volcanoes, following the routes shown in Figure 1.


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Figure 1: Flights made on 21 and 23 December 2016 (Base: Google Earth).


Visual Observations:
During the approach of the volcano, this one was quite clear. It was found that the fumaroles that border the eastern flank of the central crater were active during the flight time. Moreover, the presence of a new explosion crater on the southeastern edge of the central crater (Fig. 3), linked to its explosive activity, may be of recent phreatic origin. Pyroclastic flux deposits were evident on the southern and northern sides of the cone, however, they did not reach large distances and thus did not reach the base of the cone. The top of the cone was found to be covered with a large layer of ash (Figure 2), suggesting an important explosive activity, which distributes pyroclastic material around the cone, depending on wind direction; This activity is linked to the latest thermal alerts recorded by the Mirova system. On the south-east flank, the volcano has a type of effusive activity from the domes « Ñuñurcu », from which originated a lava flow still hot.

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Figure 2: The Sangay volcano seen from the southwest, note the large dark gray layer of ash on the top of the volcano. (Photo: M. Almeida – IG / EPN, 23/12/2016).

Thermal monitoring:
Overall, apparent maximum temperatures (TMA) recorded during flight show values below 100 ° C, thermal monitoring has identified a major crack on the southern flank of the volcano, associated with fumaroles whose TMA is 33, 3 ° C and which, in certain sectors, shows clear degassing. The new explosion crater in the southeast of the central crater recorded a TMA of 34.6 ° C. The highest temperature was recorded in the Ñuñurco domes with a TMA value of 77.9 ° C and its associated lavas of 53.1 ° C. All recorded temperatures of fumarole fields are around 20 ° C. The western dome of the volcano is almost cold (Figure 3).

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Figure 3: The Sangay volcano seen from the south-east, on the left and the corresponding thermal image in the picture on the right, you can see the hottest areas: cracks, domes and lava flows. (Photo and thermal imaging: M. Almeida – IG / EPN, 23/12/2016).


Visual Observations:
The volcano was clearly visible in its entirety, which facilitated visual and thermal observations. It has been found that when the volcano has a very low surface activity (Figure 4), fumaroles can not be distinguished by the eye from the air and no emission of gas has been seen from the vents. No significant changes were found in the morphology of the volcano.

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Figure 4: Tungurahua volcano seen from the South, no surface activity is observed. (Photo: M. Almeida – IG / EPN, 23/12/2016).

Thermal monitoring:
Thermal monitoring shows the fields of fumaroles with low temperatures as well as temperatures that have been modified by the action of solar radiation. The highest temperature was recorded in the fumarole zone below the highest peak with a TMA of 39.4 ° C and the inner crater with a TMA of 39.1 ° C. The remaining fields have variable fumarole temperatures between 23 ° C and 28.3 ° C (Figure 5).

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Figure 5: Tungurahua volcano seen from the northwest, you can see the hottest areas in the northern fumarolles area, located on the highest peak. (Photo and thermal imaging: M. Almeida – IG / EPN, 23/12/2016).


Visual Observations:
On approaching the volcano, it was quite clear (Figure 6) and the absence of degassing was observed throughout the area of the volcano. The different fronts of the glaciers on all sides of the volcano show no sign that betrays an increase in their rate of fusion. On the highest peak of the volcano (5790 meters), an important crack that cuts the ice sheet in the N-S-SE direction (north-south-south-east) was observed. The satellite photo of the Earth (Figure 7) on 27 January of this year, does not show the presence of this crack. This confirms the indications of mountain guides.

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Figure 6: The Cayambe volcano seen from the east, no surface activity, or melting glaciers is observed. (Photo: M. Almeida – IG / EPN, 23/12/2016).

Thermal monitoring:
Thermal monitoring on the Cayambe did not show thermal anomalies on the volcano, measurements in rocky areas where steep slopes do not allow snow accumulation and therefore ice formation show that Temperatures are less than 35 ° C. (FIG. 8) and which deal with the influence of solar radiation but do not correspond to thermal anomalies.
It is important to note that this overview could not see the thermal anomalies in the crack which is discussed in the chapter on « visual observations ». In other words, it is not yet possible to confirm that the origin of this crack has to do with an abnormal hydrothermal activity on the highest peak (Figure 7).

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Figure 7: Photographie, imagerie thermique et l’image de Google Earth (21 Janvier 2016), vous pouvez voir la fissure formée sur le plus haut sommet du volcan Cayambe. (Photo et imagerie thermique: M. Almeida – IG / EPN, 23/12/2016 Image satellite: Google Earth.).

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Figure 8: Les photographies et images thermiques du volcan Cayambe. Rangée du haut: vue depuis le flanc Sud, les rochers chauffés par le soleil sont observés. Rangée du bas: vue sur le flanc Nord du volcan. (Photo et imagerie thermique: M. Almeida – IG / EPN, 23/12/2016).


Observations visuelles :
Pendant le survol du volcan Cotopaxi, on pouvait voir une colonne faible mais continue de gaz se diriger vers le Nord-Ouest . Il a été observé que les évents sur le flanc Ouest et au Sud ont été actifs pendant le trajet. Les fronts des glaciers des flanc Sud ont montré des signes de fusion , observés comme une tache gris foncé sur le côté et le bord avant de ceux-ci (figure 9).

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Figure 9: Le volcan Cotopaxi vu depuis le Sud-Est, avec une faible colonne de gaz. La fonte des glaciers sur les fronts des flanc Sud est observée. (Photo: M. Almeida – IG / EPN, 23/12/2016).

Surveillance thermique :
L’analyse des images thermiques du volcan ne montre pas de changement par rapport aux dernières valeurs , les températures les plus élevées ont été enregistrées sur le flanc Est d’une valeur TMA de 58,1 ° C   et sur le flanc Sud avec 53,8 ° C , correspondant aux champs de fumerolles. Des températures élevées ne sont pas enregistrées dans le cratère, mais celui ci  a été couvert par les gaz émanant du volcan à ce moment-là. La Figure 10 montre les variations de température pour les parois latérales et le cratère du volcan Cotopaxi depuis l’éruption du 14 Août 2015 (Figure 10).

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Figure 10: Le volcan Cotopaxi vu depuis le Sud-Est, vous pouvez voir les zones les plus chaudes dans la zone de fumerolles Sud-Est , juste sous le bord du cratère et à droite du sommet Sud. (Photo et imagerie thermique: M. Almeida – IG / EPN, 23/12/2016).

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Graphique 01: Résumé des températures maximales apparentes (TMA) obtenus dans les survols jusqu’au 23 Décembre  2016, depuis le 18 Août 2015. Les courbes représentent la variation de température pour les parois latérales et le cratère; à chaque sommet (données), un bar est observé , représentant en noir l’erreur de mesure de pourcentage. (Préparé par: M. Almeida – IG / EPN).

Source : MA, PR, SA
Instituto Geofísico
Escuela Politécnica Nacional


Bogoslof ,  Aleutians Islands , Alaska :

Current Volcano Alert Level: WARNING
Previous Volcano Alert Level: WATCH
Current Aviation Color Code: RED
Previous Aviation Color Code: ORANGE

Issued: Thursday, January 5, 2017, 1:42 PM AKST
Source: Alaska Volcano Observatory
Notice Number: 2017/A11
Location: N 53 deg 55 min W 168 deg 2 min
Elevation: 492 ft (150 m)
Area: Aleutians



Volcanic Activity Summary:
AVO has just detected an escalation in seismicty beginning at about 13:24 January 5 AKST (22:24 UTC) from Bogoslof volcano. This activity is accompanied by lightning strikes detected by the World Wide Lightning Detection Network indicating that a significant explosion has occurred. Based on the intensity of these signals AVO is raising the Aviation Color Code to RED and Alert Level to WARNING. More details will be provided as they become available.

Source : AVO

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Showing 2 comments
  • Pamela Conley

    Do a lot of the explosions on Bogoslof catch the wildlife off guard or are they able to get away before they are seriously injured or killed? I noticed a great deal of wildlife call this small island home. Does the government help them at all?

    • ADMIN

      It is impossible to decide, we have no image of the island.

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