Monday, February 29, 2016

GLOBAL VOLCANISM: The Latest Report Of Volcanic Eruptions, Activity, Unrest And Awakenings – February 23 - 29, 2016! [PHOTOS + VIDEO]

Eruption of Momotombo volcano (February 21, Image: Richard Roscoe)

February 29, 2016 - EARTH - The following constitutes the new activity, unrest and ongoing reports of volcanoes across the globe.

Momotombo (Nicaragua): The volcano continues to produce on average 2-3 vulcanian-type explosions per day. Some of them seem to generate small pyroclastic flows.

Eruption yesterday evening.

WATCH: Spectacular video by Richard Roscoe that was taken last week.

Sinabung (Sumatra, Indonesia): Over the past days, activity at the volcano seems to have picked up. The frequency and size of explosions from the summit have increased and generated several ash plumes that rose up to approx 3 km height above the summit.

In addition, collapses of parts of the lava lobe generated small to moderate pyroclastic flows that traveled up to 3 km down on the ESE side. One of them on Saturday reached again the (already mostly destroyed and abandoned) village of Simacem on the ESE flank at only 3 km distance from the crater.

Explosion from Sinabung on February 25. (Image: Endro Lewa / Facebook)

Eruption with lightning on February 25. (Image: Endro Lewa / Facebook)

Explosion at Sinabung. (Image: Endro Lewa / Facebook)

Destroyed houses in Simacem (Photo: Andi / VolcanoDiscovery Indonesia)

Whether this apparent increase in activity caused by and actual increase in magma and or gas output, or simply a process of releasing accumulated pressure and instabilities on the already emplaced lava lobes on the steep flanks of the volcano is unclear.

For the local population, this means the long-lasting (more than 2 years now) crisis has no end in sight: the exclusion zone of 4-5 km radius around the volcano (depending on which sector) remains in place. More than 9500 people evacuated from villages in this risk area continue to live in a total of 9 now semi-permanent shelters.

Dallol hydrothermal field (Ethiopia):  One of our groups visited Dallol last week during our recent Danakil volcano expedition. The hydrothermal activity was observed to be very intense, with many colorful ponds and hot springs.

Expedition leader Enku reported:

"Dallol is back to its original status with every bit of the geothermal fissures which are full of activity with gas and liquid chemicals washed out by the hot ground water. I have never seen Dallol like this before in my entire 12 years of Afar Depression trip."
Green and yellow salt pond at Dallol (Image: Enku Mulugheta)

Green lake at Dallol (Image: Enku Mulugheta)

Salt lake at Dallol (Image: Enku Mulugheta)

Tungurahua (Ecuador):  Two moderately large explosions occurred at the volcano yesterday noon from 12:12 local time. The first and larger explosion produced an ash plume that rose approx. 5000 meters above the summit.

The ash plume dispersed mainly to the west and northwest where ash fall occurred in areas including Choglontús, Pillate, Cahuaji and El Manzano.

According to IGEPN, the eruption - which came after a 3 months interval of quiet since last November - was most likely NOT the result of new magma, but instead of accumulated gas pressure in the upper conduit.

Eruption plume of Tungurahua volcano (Image: J.L Espinosa-Naranjo @Ambalaser / Twitter)

Magmatic gasses (H2O, CO2 etc) still contained in older magma inside the conduit was being released quietly as the magma continued to cool and crystallize, but most of these gasses were being trapped beneath a solid plug. With time, the gas pressure increased to the critical point: the plug gave way in yesterday's explosions.

The explosion itself, a typical so-called "vulcanian"-type eruption, was preceded only by a short (lasting little more than an hour), but intense seismic swarm of shallow earthquakes caused by internal fluid movements and rock fracturing as pressurized gasses started to disintegrate the overlying plug.

Shiveluch (Kamchatka):
Based on satellite data, Tokyo VAAC reported an eruption plume from the volcano that rose to estimated 21,000 ft (6.4 km) altitude yesterday evening and drifted NW.

The volcano overall has been a bit calmer recently.

This and a similar report a few days ago indicate that activity continues, and produces occasional moderate-sized explosions and/or pyroclastic flows event from the active lava dome. In many cases, cloud cover prevents visual observation of the volcano from the webcam.

Etna (Sicily, Italy): An unusual eruptive episode occurred yesterday morning from the volcano's NE crater (the least active of the summit vents over the past few decades). Incandescent bombs were ejected above the rim of the crater and an ash plume rose several hundred meters.

Whether this is the beginning of a more significant eruptive phase, after a period of relative calm since the violent paroxysms of Voragine summit crater in early Dec 2015 remains to be seen.

Eruption of Etna's NE crater (INGV Catania)

Thermal image of the eruption showing incandescent material ejected from NE crater

INGV published the following report:

"During the month of January 2016, Etna's eruptive activity has maintained rather low levels. Early that month, a few weak ash emissions occurred from the 25 November 2015 vent located high on the eastern flank of the New Southeast Crater (NSEC) cone; similar phenomena were repeated during the last week of January and once more on the morning of 6 February. During the same time interval, degassing from the Northeast Crater (NEC) were sometimes accompanied by the emission of minor traces of ash.
A field survey was carried out in Etna's summit area by INGV-Osservatorio Etneo (INGV-OE) staff on 19 February. During the visit, no ash emissions occurred from the summit craters, but the NEC was the site of intense degassing from its open conduit; due to strong wind it was not possible to hear if there was any acoustic activity coming from the crater, which typically produces loud bangs and rumblings. At the other summit craters, degassing was limited to extensive fumarolic areas along the crater rims. The eruptive products of December 2015, which fill the single huge depression constituted by the Voragine and Bocca Nuova, were covered with snow except in the areas where vapors were emitted from fissures formed by compaction of the deposit.
At 03:22 UTC (=local time -1) on 23 February 2016, the video and thermal cameras of the INGV-OE recorded an explosive event at the NEC, which ejected incandescent pyroclastics to several tens of meters above the crater rim (see image at top left, recorded by the high-definition visual camera at Monte Cagliato, on the east flank of Etna - click on image for larger version) and produced a dark ash plume that was blown northeastward by strong wind. The images at center left (click on image for larger version) were recorded by the high-sensitivity camera on the Montagnola (EMOH, on the upper south flank of Etna) and also show a few lightning flashes in the ash cloud.
The images recorded by the thermal surveillance camera at Monte Cagliato (EMCT, see images at bottom left - click on image for larger version) show a conspicuous anomaly generated by the explosion, which was followed by minor ash emissions that gradually diminished; as of the late morning of 23 February, intermittent and weak ash emissions are continuing from the NEC." (INGV Catania)

Colima (Western Mexico): The new lava dome in the summit crater continues to be active (and probably is growing) as bright glow visible at night suggests.

Small emission and glow from Colima's summit crater.

Explosive activity on the other hand has decreased recently.

Reventador (Ecuador): The eruptive activity of the volcano continues with no significant changes, at moderate to high levels, as IGEPN reports on a daily basis.

Lava arrives at the summit crater where small explosive activity (probably strombolian-type) takes place. During yesterday, based on seismic data (the volcano is mostly hidden in clouds), 56 small explosions were registered. This morning, an ash emission was also detected by Washington VAAC.

Cotopaxi (Ecuador): Surface activity of the volcano has been mostly low during the past weeks, characterized by degassing / steaming and occasional very weak ash emissions.

According to IGEPN, the level of most monitored geophysical parameters (SO2, volcanic earthquakes, volcanic tremor, deformation) have returned to their pre-eruption background levels.

However, the overall seismic activity of the volcano is still elevated and some few deep-seated explosive events are being recorded (on average 1-3 / day).

Cotopaxi volcano.

This type of activity possibly indicates that a magma source remains active inside the edifice. The most likely scenario of the coming days to weeks is that surface activity remains at a low level and or continues to decrease, with intermittent small ash emissions possible that would not affect but immediate areas surrounding the volcano. However, even though much less likely now, an increase in internal and external activity of the volcano cannot be excluded either.

Although not directly connected to its activity, as a secondary effect, the risk of lahars (mud flows triggered by melt water) remains elevated.

- Volcano Discovery .

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