Thursday 25 February 2016

Volcanos

Roundup of Global Volcanic Activity

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. 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.

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. Explosive activity on the other hand has decreased recently.

Momotombo (Nicaragua): Activity has been calmer during the past two days. No new significant explosions occurred in the interval, but incandescence remains visible at the summit crater, indicating small extrusive activity continues.

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). 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.

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