Sunday, 28 April 2013

Volcanos

Roundup of Global Volcanic Activity:


Stromboli (Eolian Islands, Italy): An increase in activity occurred yesterday. Lava started to effuse from one or two vents at the base of and on the outer flank below the NE hornito. It is currently extending on the upper part of the Sciara and produces strong rockfalls that reach the sea. The seismic signal shows increased tremor and continuous rockfalls on the Sciara, as well as large explosion signals at intervals of approx 15-30 minutes.


Etna (Sicily, Italy): Activity has continued to increase with near continuous strong strombolian explosions from the New SE crater, but it seems that the climax of the paroxysm with sustained lava fountains is yet to come, possibly very soon. The tremor has reached higher levels than during most of the previous paroxysms, but still rises. Strong strombolian-type explosions, probably accompanied by effusion of small lava flows continued all night from the New SE crater and produced strong glow visible through the fog around the summit. Rumblings were heard in nearby villages, but fog and clouds have been preventing detailed observations. The tremor has risen to high levels comparable with those during previous paroxysms, then decreased a bit and seems now to increase again. This pattern looks very similar to the 12 April paroxysm, one which was preceded by a long phase of very strong explosions, that culminated in lava fountaining only after the tremor had reached its peak.


Batu Tara (Sunda Islands, Indonesia): Ash plumes rising to 7,000 ft (2.1) km elevation from relatively strong strombolian activity were reported both yesterday and today. (VAAC Darwin)


Santa María / Santiaguito (Guatemala): The rate and size of explosions from the lava dome has risen a bit when compared to the previous week. Some of the explosions, about 1-2 per hour, produce plumes almost 1 km high.


Pacaya (Guatemala): Weak strombolian activity from the Mackenney crater, well visible at night, continues and has been showing a gradual increase over the past days. This is also evident from the seismic recording. Some explosions can be heard in up to 3 km distance.


Fuego (Guatemala): The effusive eruptive activity continues to increase slowly. Two branches of the lava flow advanced to 500 m length towards the Ceniza and 400 m length to the Taniluyá canyon. Rockfalls from the flow fronts produce incandescent avalanches that reach the vegetation line. At the summit, strombolian activity has been weaker today, but continues with infrequent small explosion that eject bombs to 100 m height and produce small ash plumes. Activity has been increasing. Continuous stronger tremor today suggests an increase in effusion rate today. In INSIVUMEH's report from yesterday, the new lava flow was 400 m long and produced small avalanches towards the Ash Canyon. The number of explosions rose to 17, producing gray ash plumes rising 600 m above the crater and drifting 8-10 km to the west and SW. They were accompanied by weak rumblings and locomotive-like degassing sounds. Incandescent material was seen rising 100-200 m at night.


Sangay (Ecuador): Brief ash emissions were reported observed through satellite yesterday around noon. Ash plumes rose to about 25,000 ft (7.6 km) altitude or about 2 km above the volcano. There is no ground monitoring, and only rarely direct observations become available from the very remote and difficult-to-access volcano. It is likely that usually small strombolian-type activity has been going on in the summit crater for some time. This activity usually goes unnoticed, unless explosions occasionally increase and produce more significant ash plumes such as yesterday.

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