December 02, 2015. EN. Etna , Momotombo, Yellowstone .

Home / blog georges Vitton / December 02, 2015. EN. Etna , Momotombo, Yellowstone .

December 02, 2015. EN. Etna , Momotombo, Yellowstone .

December 02, 2015.



Etna, Sicile :

In recent weeks the strombolian activity in the crater of Voragine, one of the four summit craters of Etna, continued without major changes. The activity consists in intens explosions and variable frequency, with the emission of incandescent bombs sometimes with small amounts of volcanic ash. In some cases, the bombs are projected on the side of the internal crater of the Voragine and up to tens of meters above the crater rim. The photo below, taken by Francesco Ciancitto (INGVOsservatorio Etneo) on November 19, 2015, shows a typical explosion with the launch of incandescent bombs and a small ash plume, seen from the western edge of the Voragine.

Since early November, the amplitude of volcanic tremor showed a series of transitions, with a clear increase of the signal amplitude and a change of the source of tremor , to the surface and a position below the center from the top , to the Southeast and the South. Some of these events were accompanied by a visible increase outgassing in the New Southeast Crater (NCSE), especially from a fumarolic area on the east side of the top of the cone, where the thermal camera of Monte Cagliato (EMCT) also recorded small thermal anomalies. The episode of the volcanic tremor amplitude , on the night of 7 to 8 November was followed by the small explosion described in the updated of November 8, which took place near the eastern end of the NCSE . Activities in the Voragine showed no change over the increases in the amplitude of volcanic tremor.


After another episode of high amplitude of tremor, 20 to 22 November, during the night of November 24 to 25, there was a small strombolian activity in the same area of fumaroles on top of the eastern flank of the cone NCSE. This created a large thermal anomaly on the images of EMCT. In the afternoon of 25 November from the same point, have produced small ash emissions, one of which is visible in the photo on the left, taken from Catania in the late afternoon of the same day by Boris Behncke (INGVOsservatorio Etneo). The ash emissions have ceased shortly after sunset. The next night were observed some rare and low emissions of the mouth that had produced emissions of ash. On the morning of November 27, it was noted a further increase in the volcanic tremor amplitude that lasted several hours. The bad weather did not allow checking whether this episode was accompanied by volcanic activity. On the morning of November 28, it was possible to observe the continuation of intense degassing of the eastern flank of the NCSE cone. However, it was noted the absence of new eruptive products.

The good visibility on 29/30 November revealed the presence of a new small crater (« pit crater« ) on top of the eastern flank of the cone of the New Southeast Crater (NCSE), which is clearly visible on the pictures above, taken on Nov. 30, 2015 from Giarre by Turi Caggegi. It’s the mouth that opened by strombolian activity during the previous week, and is located a few tens of meters below the eastern edge of the NCSE, with a diameter of about 15-20 m. This new crater mouth is still the seat of a low outgassing, while at night a faint glow was observed inside. The available data do not allow to characterize the eruptive activity that began on November 25; if this activity was present, it would still be intracraterique.




The formation of new pits craters   is a very common phenomenon on Mount Etna and can occur in the summit area during and after flank eruptions  . And we know that each of the current summit craters – Crater Northeast (1911), Voragine (1945), Bocca Nuova (1968), the Southeast Crater (1971) and NSEC (2007-2009) – are born as a « Pit crater ». The structures of this type are often also formed inside the craters or on the flanks of their cones. At NCSE, a small crater in the well (so called « Pittino ») was established in August 2012 to become one of the main blowhole for several paroxysms in 2013. Even during the long eruptive episode from January to April 2014, it was opened a pit on the eastern edge of NCSE with dimensions similar to that formed these days. This crater was buried by the products of eruption from the episode of mid-June 2014.


Source : INGV / B Behncke.

Photos : Francesco Ciancitto , B Behncke , Turi Caggegi.



Momotombo, Nicaragua :


Volcanic activity of Momotombo, Tuesday 1st December 2015.

At 7:49 am, there was an explosion of gas and ash in the crater of the Momotombo volcano, which rose to a height of about 1,000 meters above the volcanic crater. The ash was scattered to the southwest.
Then at 8:17, 8:42 ET 8:55, gas explosions and ash, which reached a height of about 300 meters above the crater were recorded.
Gas expulsions continue after the initial explosion and gas and ash explosions can still occur, seismic and volcanic events can be felt by the population.

Imagen de cortesía que muestra las cenizas expulsadas por el volcán Momotombo.

The Momotombo is a volcano which since 1500 years recorded 16 eruptions of moderate magnitudes, except that of the early seventeenth century (1605-1609), which was the largest in historical time with large amounts of volcanic material deposits in the town of Puerto Momotombo, in the southwest of the volcano.
The last eruption, which has produced abundant gas explosions, volcanic ash and lava flows occurred in the year 1905, during five days of eruptive activity, but it was not a violent eruption with « pyroclastic flows« .
The INETER continues to closely monitor the activity of active volcanoes and will continue to report on these developments.


Source : INETER




Yellowstone, Etats-Unis :


44°25’48 » N 110°40’12 » W,
Summit Elevation 9203 ft (2805 m)
Current Volcano Alert Level: NORMAL
Current Aviation Color Code: GREEN

During November 2015, the University of Utah Seismograph Stations, responsible for the operation and analysis of the Yellowstone Seismic Network, reports 155 earthquakes were located in the Yellowstone National Park (YNP) region. The largest event was a micro earthquake of magnitude 2.8 on November 24, at 04:06 PM MST, located about 16 miles north of Lake, WY.

November 2015 seismicity is characterized by two earthquake swarms.

1) On-going seismicity continues near West Yellowstone, MT where a swarm of 90 earthquakes occurred November 6 — 10. The largest swarm earthquake (magnitude 2.3) occurred November 7, 11:59 AM MST, located 7 miles north of West Yellowstone, MT.

2) A small swarm of 13 earthquakes occurred November 24th and 25th. The largest swarm earthquake (magnitude 0.9) occurred November 25, 1:08 AM MST, located 9 miles southeast of West Yellowstone, MT.



Afficher l'image d'origine

Earthquake sequences like these are common and account for roughly 50% of the total seismicity in the Yellowstone region.

Yellowstone earthquake activity in November is at normal background levels.

Ground deformation
GPS stations in Yellowstone continue to show little or no ground movement. (click on Static Plots / Time Series)

The Yellowstone Volcano Observatory (YVO) provides long-term monitoring of volcanic and earthquake activity in the Yellowstone National Park region. Yellowstone is the site of the largest and most diverse collection of natural thermal features in the world and the first National Park. YVO is one of the five USGS Volcano Observatories that monitor volcanoes within the United States for science and public safety.


Source : YVO

Photo : wallpaperswiki

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