From: NASA MODIS Web
Posted: Tuesday, June 14, 2011
Near the center of the image, a long plume of vog blows from Ambrym Island towards the west.
The island is the summit of a massive basaltic volcano, with a 12-km wide caldera. Ambrym is one of the most active volcanoes of the New Hebrides arc, with a history of frequent eruptions for about the last 2,000 years. The nearly annual eruptions in historic time are noted for emission of sulfur dioxide gas, which often results in spectacular vog (volcanic fog). Further south, a large red circle marks a thermal anomaly (hotspot) associated with Yasur, an active volcano on the island of Tanna. On June 1, the Vanuatu Geohazards Observatory raised the Alert Level for Yasur to 3 (on a scale of 0-4) following increasing explosive activity in May. Strong explosions from all three active vents were reported, along with ash emission and bomb ejections beginning May 31. On June 13, the Vanuatu Geohazards Observatory reported that the volcanic activity has decreased since early June, yet constant strombolian activities with occasional ejections of lava bombs still occur around the volcano. Yasur is considered to be the best known and most frequently visited of the volcanoes found on Vanuatu. It has been in more-or-less continuous Strombolian and vulcanian activity since Captain Cook reported ash eruptions in 1774, although eruptions may have been continuing for the past 800 years.
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