Deadly Mount Sinabung eruption, May 21, 2016

Sinabung as viewed from the east.
Photo by Tom Casadevall, U.S.G.S., 1987

Mount Sinabung in the North Sumatra province of Indonesia, erupted on Saturday killing seven people in a village.  The village, Gembar, is one of four villages inside a 2.5 mile danger zone from which 5,000 residents were evacuated at the time. Villagers still enter the zone intermittently to tend to property. A video showing parts of the eruption and its ashy aftermath is available from The Guardian here.
     Sinabung is a highly active stratovolcano that rises to an elevation of 2460 meters. It is part of a subduction zone setting where the continental crust is >25 kilometers thick. The major products are andesite, basaltic andesite and dacite. There are four active craters at the summit. All four craters discharge sulfurous gases and form sulfur deposits which are mined by the local people.
    There are unconfirmed reports of an eruption in 1881, and solfataric activity was noted high on the volcano in 1912. It appeared to be dormant from this date until an explosive eruptions (VEI 2) in the summer of 2010. The eruption of August 27th was phreatic, with the initial emission of a grayish white plume followed by black plumes that reached 2000 m above the crater. The rocks and ash erupted came from altered rock in the crater and its deeper hydrothermal system.
    The events of 2010 were followed by a lava dome-forming eruption accompanied by explosive eruptions in September, 2013. Lava extrusion continued through 2014 at a rate of about 3.5 cubic meters per second, reaching about 0.1 cubic kilometer in volume. Sixteen people were killed in February 2014, and 30,000 local residents had to be evacuated. Magma mixing before the eruption is indicated by the presence of magic blobs and "plagioclase microlites more calcic than the phenocryst rims," and absence of a reaction rim on hornblende phenocrysts (Nakada et al., AGU abstract, 2014).
     As of the date of this post, the area remains under high alert and efforts are being made to evacuate any people in the danger zone.

Mayon and Bardarbunga volcanoes.

Mayon volcano, copyright Tom Tam shot from
Lingnon hill in Daraga Town near the volcano and his home

Mayon, a stratovolcano of nearly perfect symmetry, in the Philippines is again active. It is one of the most active volcanoes in the world. It has erupted 49 times in the past 400 years.  Coincidentally, the most destructive eruption was in 1814, a year before Mount Tambora erupted, with the emission of ash that led to the "Year without a summer" in 1816.  New reports today are that more than10,000 people from around the volcano are being evacuated.

The volcanic activity is being actively reported on Wiki here, and here is the link to the Philippine Institute of Volcanology and Seismology, PHILVOLCS. The monitoring network has detected 39 rockfall events that are "ascribed to incipient breaching of the growing summit lava dome." Continuing seismicity indicates either magma intrusion or volcanic gas activity, and there is sufficient magma in the summit crater to cause a red glow. PHILVOCS has raised the alert level to Level 3, stating that a hazardous eruption is "possible within weeks." A Permanent Danger Zone extends out to a 6 km radius, and an Extended Danger Zone to 7 km. These are being evacuated because of danger of rockfalls, landslides, and lava/ash/mud flows. (Level 3 is the third highest level of alert, following "eruption" and "imminent eruption.")

Bardarbunga in Iceland continues to be active seismically and as of a flyover of the Holuhraun fissure on Sept. 12, about 200 cu meters of magma per second are erupting. Lava is flowing nearly 20 km from the vent.