September 16 , 2017. EN.  Dieng , Ambae , Guallatiri , Reventador .

Home / Ambae / September 16 , 2017. EN.  Dieng , Ambae , Guallatiri , Reventador .

September 16 , 2017. EN.  Dieng , Ambae , Guallatiri , Reventador .

September 16 , 2017.

 
Dieng , Indonésia:

 

Visual observation.

Visual observation of the Dieng volcano in the period from June 2017 to September 14, 2017 generally showed sunny weather – cloudy to rain, with maximum precipitation of 88.9 mm. The wind blows slowly from the South, East, West and North of the Sileri Crater. A low-pressure gas emission is observed in white, with a low to medium intensity, with a maximum height of 10 meters. On 2 July 2017 at 11:54:24 a phreatic eruption was observed, with thick white smoke, rising ± 150 meters with high pressure.

Observation of earthquakes.
The observation recorded 24 distant tectonic earthquakes, 173 local tectonic earthquakes (2 felt M4, 1 felt M2), 51 deep volcanic earthquakes (VA), 10 shallow volcanic earthquakes (VB ), 12 Tornillo type earthquakes, 485 emission events, 1 phreatic eruption.

Measurement of gas concentration and temperature of the crater.
The measurement of the water temperature of the Sileri crater from July 8, 2017 to September 14, 2017 at 22:30 shows a temperature increase from 90.7oC to 93.5oC. And the soil temperature in the Sileri crater also shows an increase from 58.6 oC to 69.4oC. The temperature measurement of the crater emissions from May 25, 2017 to September 13, 2017 also shows an average increase from 57.3 ° C to 62.7 ° C. The concentration of CO2 in the crater from May 25, 2017 to September 13, 2017 ranged from 0.22% to 0.24%. and showed no improvement.

Evaluation .
The temperature and concentration of CO2 gases in the crater tend to be normal, while the temperature in the Sileri crater tends to increase since July 8, 2017.
Seismic monitoring since January 2017 and until September 13, 2017 at 06:00 shows a number of earthquakes that fluctuate, but since September 13, 2017 and until September 14, 2017 at 21:00, there is a continuous tremor with a amplitude of 0.3 to 1 mm, dominating to 0.5 mm.

Conclusion:
Based on the results of the analysis of the visual and instrumental data as well as the potential threats of danger, G. Dieng’s level of activity is increased from Level I (Normal) to Level II (Waspada).

Source : VSI
Photo : Paul Fohl

 

Ambae , Vanuatu :

FYI, Lembenben volcano on Ambae erupt last night.

The Volcano has been at level three for the last few weeks but yesterday it erupted. the Provincial Disaster committee and Red Cross branch officers and the Penama Red Cross Emergency Response Team (ERT) Volunteers have already deployed to south and West Ambae to advocate on preparedness, they also trying to conduct an evacuation plan once every team who has been deployed return with their situation report.

AMBAE VOLCANO ALERT BULLETIN No10 issued by the Vanuatu Meteorology and Geohazards Department (VMGD) on 15th September 2017 at 11:59AM :

The Alert Level for Ambae volcano remains at the Level 3.
This means that the Ambae volcano is in a minor eruption state. At this Alert Level, the volcanic activity is likely to continue to increase or decrease to its normal level of unrest at any time. Danger Zone A at Ambae volcano is closed (Shouldn’t be Access) (See red dot circle – photo below).


This is a reminder to all visitors to must observe this volcano away from the Danger Zone A which is about 3 km radius from Manaro Voui lake. Villages and communities of Ambae Island, especially those in the prevailing trade winds direction will expect volcanic gas, ash falls and acid rain that may cause foliage fumigation hence damage garden crops.
It’s very important that communities, villages, visitors and travel agencies seriously consider this information.

Source : Vanuatu Red Cross , Geohazard.
Photo : Peter Vibs

 

Guallatiri , Chile :

Special Volcanic Activity Report (ARAV), Arica Region and Parinacota. 14 September 2017.19: 8 pm (local time).

The National Geological and Mines Service (Sernageomin) of Chile announces the following information obtained from the monitoring teams of the National Volcanic Surveillance Network (RNVV), processed and analyzed at the Southern Andes Volcanological Observatory (OVDAS):

Yesterday, September 14, 2017 at 6:32 pm local time (9:32 pm GMT), monitoring stations near the Guallatiri volcano recorded one (1) volcano-tectonic earthquake (associated with rock fracturing). The event was located 14.6 km south-southwest (SSO) of the main crater.

The location obtained was as follows:
TIME OF ORIGIN: 12h11 Hl (GMT-3)
LATITUDE: 18 ° 24’23.4 « South
LONGITUDE: 69 ° 08’0.6 « West
DEPTH: 9,7 Km
LOCAL MAGNITUDE: 3.5 ML

NOTES:
At the time of publication of this report, two replicas of lower magnitude were recorded. There is no information from authorities or communities in neighboring areas about the feelings of these events.
The volcanic technical alert is maintained at the Green level.
The Sernageomin continues with on-line monitoring, and will inform about changes in the volcanic activity of the region.

Source : Sernageomin

 

Reventador , Ecuador :

 

The eruption continues, alternating between effusive and explosive activities.

Summary.
In recent months, the eruptive activity of the Reventador volcano has varied with lava flows (from June 24 to July 1 and August 23 to 24), periods of frequent small explosions (August) and periods of explosions less frequent but moderate to large (July and September). There is no evidence of a significant decrease or increase in the volcano’s internal and external activity at this time, suggesting that the eruption will continue with the alternation of effusive activity lava) and explosive in the coming days / weeks without major direct affect to the communities surrounding the volcano. It is important to note that the accumulation of materials in the gullies that descend from the volcano could generate lahares in case of heavy rains.

Figure 1. Infrared image of the lava flows from the north wind and the southern wind at the top of the El Reventador volcano on August 23, 2017 (image: M. Almeida, treatment: M.-F. Naranjo).

Surface activity.
Thanks to the cameras installed on the volcano and the Washington VAAC alerts, surface activity was observed continuously and in real time. Between the end of June and the end of July, an explosive activity of moderate intensity was observed with ash emissions reaching <1000 m above crater level, westward (between NW and SW) and bearing blocks up to 800 m below the level of the crater. Activity increased from 21 to 22 July with columns of ash up to 2500 m (Figure 2) and blocks rolling on the sides of the volcano up to 600 mnn.


Figure 2. Elevations of ash columns detected by satellites (source: Washington VAAC, compilation: M. Encalada).

In August, a decrease in activity intensity was observed, mainly characterized by columns of ash with heights less than 1000 m to SW and small avalanches of hot material in the upper part of the volcano. At the end of the third week of August, there was an increase in eruptive activity with constant incandescence in the crater, with more frequent eruption columns reaching 2000 m (Figure 2). An overflight carried out on 23 August confirmed the simultaneous extrusion of lava flows along the NE, ENE, ESE, S and WSW flanks from 2 vents located at the top of the volcano, which also produced significant explosive activity. With respect to the June activity, these new lava flows generated a strong thermal anomaly detected by the satellites (FIG. 3). It was also observed that the ash columns were wider and more continuous. Gas measurements during the 23 August flyover did not indicate an increase in SO2 flow over previous flyovers.

Figure 3. Intensity of thermal anomalies obtained by satellites (source: MODVOLC-MIROVA, compilation: M. Almeida). The red squares identify the anomalies associated with the lava flows of June and August 2017.

Figure 4. Photo (left) and thermal image (right) of the lava flows of August 2017 in the summit zone of the Reventador (photo: P. Ramón, thermal image: M. Almeida, treatment: M.-F. Naranjo).
Since this last lava episode, the ash columns observed by the Washington VAAC have been more frequent with altitudes up to 3500 m to the W and NW. Similarly, during the explosions, blocks were observed which covered almost all the upper cone and descended up to 900 m.

Figure 5. Explosion with descent of incandescent blocks on all flanks of the volcano up to 900 m on September 11, 2017 (source: IG-EPN).

Seismic and acoustic monitoring.
Seismic and acoustic activity on the Reventador volcano has shown variations over the past few months, coinciding with variations in surface activity. The number of explosions fell after the June 22-24 eruption at 34 explosions / day (Figure 6). However, it was observed that these explosions had higher acoustic energy, especially from the third week of July (Figure 7).

 

Figure 6. Number of seismic events on the Reventador volcano between 01/06 and 14/09/2017 (source: IG-EPN). LP: long period, EXPL: Explosions, TRESP: spasmodic tremor.

In August, there was a slight increase in the number of explosions (40 / day), harmonic tremors (4.5 per day) and long-term events (Lps reaching 84.6 per day) new phase of lava emissions at the end of the third week of August. However, at the same time, a decrease in the size of earthquakes and, even more, of acoustics (Figure 7).

 

Figure 7. Seismic amplitude (above) and sound pressure (below) of explosions on the Reventador volcano between 01/07 and 14/09/2017 (M. Ruiz). Blue: July, green: August, red: September.

During the last week of August to the second week of September, there was a decrease in the total number of events (73 events / day, 19 explosions / day), but according to the seismic acoustic analysis, a significant increase in the acoustic pressure of the explosions with a slight increase in the seismic amplitude (FIGS. 7 and 8). Figure 7 shows that the 6 largest explosions with an acoustic component of the last quarter took place from 28 August, including the 2:35 explosion on 9 September, which reached a pressure of 514 Pa. pressure of 2627 Pa estimated at 1 km of the crater. In 2005, the highest value was 1.5 Pa (Johnson and Ripepe, 2011).


Figure 8. Seismic recording (above) and infrasound (underneath) of the September 9th explosion at 2:35 UT (Universal Time: local time + 5 hours) (Mr. Ruiz). Note the increase in the seismic amplitude induced in the REVS station by the arrival of the acoustic wave.

Interpretation.
Visual observations, seismic-acoustic and satellite data indicate variability in the eruptive activity of the Reventador volcano. Based on the last three months of activity, it is suggested that lava flows in June and August were associated with periods of high extrusion rate (magma outflow) that allow the magma to exit more easily and to form streams of lava. Probably, the phases of high extrusion rates are caused by pulses feeding a magmatic tank under the volcano. The periods of highest explosiveness (end of July and September) are associated with lower emission rates where a more viscous magma does not permit continuous degassing and increases the internal pressure of the gas, which implies explosions more violent.

Eruptive scenario
Based on the interpretation of recent eruptive activity, the following potential eruptive scenario is formulated, valid in the short to medium term (days to weeks), if there are no significant changes in the parameters of monitoring. Explosive activity is expected to change to return to early August levels with more frequent but smaller explosions. A new flux of magma could trigger new streams of lava. Eruptive activity should be maintained high as there is no evidence of a significant increase or decrease in internal and external activity.
The main phenomena associated with eruptive activity are explosions with ballistic projectiles affecting the volcanic cone, small pyroclastic flows, and weak to moderate ash columns that do not pose a direct threat to the communities surrounding the volcano. It is important to note that the pyroclastic fluxes associated with the frontal collapse of lava flows in June and August increased the amount of sediment in the drains descending from the volcano. This could lead to the formation of lahars in case of heavy frequent rains on the Reventador.

Source : IGEPN

Recommended Posts

Leave a Comment

Nous contacter

Nous ne sommes pas disponibles pour le moment. Mais vous pouvez nous envoyer un email a l'aide du formulaire ci-dessous.

Not readable? Change text. captcha txt

Start typing and press Enter to search