Thursday, 31 March 2016

Volcanos

Roundup of Global Volcanic Activity

Stromboli (Eolian Islands, Italy): The activity at the summit craters has been (comparably very) low recently. However, small strombolian explosions continue to occur at irregular rates of 30-60 minutes intervals, mainly from western vent.

Etna (Sicily, Italy): Intermittent weak to moderate ash emissions (presumably from older pulverized rock) have been occurring from the North-East crater, where also weak incandescence can be seen at night. Apart from this and an incandescent fumarole on the New SE crater, no other significant activity is currently occurring at the volcano. Tremor levels have been low.

Shiveluch (Kamchatka): The extrusive-explosive activity of the volcano continues at moderate rate. Glowing avalanches from the active lava dome and strong degassing indicate ongoing magma supply. Occasionally, explosions and larger avalanches that turn into pyroclastic flows occur as well and generate ash plumes that rise several 1000 meters. Last evening, Tokyo VAAC reported an eruption that sent an ash plume to 20,000 ft (6 km) altitude. Whether it was caused by an explosion or avalanche is unknown - only the top of the plume was visible on webcam imagery.

Chikurachki (Paramushir Island): A new eruption is occurring from the remote volcano on Paramushir Island immediately to the south of the Kamchatka peninsula.

Since 29 March, ash emissions have been seen on satellite images. The ash plume increased yesterday, reaching altitudes of 3-4 km (9-12,000 ft) and extending up to 150-200 km into south- and southwesterly directions. KVERT raised the Aviation Colour code to orange (as many trans-Pacific flight routes pass nearby) and warns that "ash explosions up to 32,800 ft (10 km) a.s.l. could occur at any time. Ongoing activity could affect international and low-flying aircraft."

Alaid (Northern Kuriles): Eruptive activity of some sort continues at the volcano. This is evidenced by a strong thermal signal detected and a gas plume extending south of the small island, both detected on satellite imagery. Contrary to nearby Chikourachki (that started to erupt 29 March), Alaid seems not to have produced any ash recently; no such darker-colored fresh deposits can be seen on the snow-covered flanks or in the plume. This suggests that the activity, at the moment, is non-explosive and confined to the summit crater, perhaps in the form of a small active lava lake.

Sinabung (Sumatra, Indonesia): The volcano continues to produce explosions and occasional small to moderate pyroclastic flows. Early on Tuesday morning, around 05:40 local time, a collapse of parts of the sticky lava lobe on the SE flank generated a pyroclastic flow that reached approx. 3 km length.

Soputan (North Sulawesi, Indonesia): In its latest report, VSI describes continuing elevated seismic activity, including shallow volcanic earthquakes and avalanches that indicate slow magma extrusion from the main vent. Visible activity during the past weeks otherwise consisted in moderate degassing generating a plume of 20-100 m height. The volcano's alert level is maintained at "siaga" ("alert"), or 3 on the Indonesian scale of 1-4 and recommends an exclusion zone of 4 km radius around the summit of Mt. Soputan.

Makian (Halmahera): Seismic unrest continues at the volcano with a weak tendency of increase in shallow volcanic earthquakes during the past weeks, possibly related to the ascent of a new magmatic body. No surface changes or other alarming signs have been observed at the volcano. While an eruption is not considered likely to be imminent, VSI maintains the alert level 2 (on a scale of 1-4) and advises locals and visitors not to climb Makian's Kie Besi volcano and stay away from the summit within a radius of 1.5 km distance.

Kerinci (Sumatra): A small eruption occurred at the volcano yesterday morning around 07:00 local time. An ash plume rising a few 100 m from the summit crater was observed.

The nature of the eruption (likely a phreatic explosion) is unknown. As safety precaution, access to the volcano's summit, Indonesia's highest volcanic peak and a popular climbing destination, was closed.

Colima (Western Mexico): The activity of the volcano has decreased overall. Explosions have been mostly weak and relatively rare (a few per day) and the previously continuously visible glow at the summit crater, indicative of the small new lava dome, has recently been visible only during increased degassing or explosion events. This in turn suggests that the growth of the dome has been very low or even stopped for now.

Popocatépetl (Central Mexico): No significant changes in activity have occurred at the volcano recently despite a series of stronger explosions during the past days. One explosion on Tuesday afternoon generated an ash plume that rose up to 3.5 km, and another one during the following night was seen ejecting abundant incandescent material outside the summit crater. During 29-30 March, CENAPRED recorded an increase of degassing events ("exhalations") and 4 explosions (an average value), as well as two small shallow volcanic earthquakes and 30 minutes of harmonic tremor. Following the larger explosion in the afternoon of 29 Mar, the International Airport of Puebla was temporarily closed.

Bright glow from the summit crater indicates that magma slowly continues to arrive there, filling the inner crater, a process that is regularly interrupted by the explosions (that usually destroy parts of the accumulated, cake-like lava dome again).

Nevados de Chillán (Central Chile): Intermittent ash emissions re-appeared at the volcano during the past days. The emissions originated from several vents, involving both the Arrau crater and the new summit pits that had formed in early and late January this year.

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