Increased seismicity, characterized by elevated levels of continuous tremor, lava fountaining, and ash emissions as high as 4.5 - 6 km (15,000 to 20,000 feet) above sea level have been occurring at Veniaminof volcano, Alaska, on the morning of August 30th. Latest AVO weekly update states that the ongoing episode of activity is some of the strongest unrest detected at the volcano so far. Although the activity at present is primarily lava fountaining and moderate ash emission, it is possible, but not certain, that conditions may continue to escalate, and higher rising, more ash rich plumes may be generated.
Throughout the past week, the volcano has experienced fluctuating levels of seismic activity characterized by alternating periods of relatively continuous low-level tremor and discreet bursts of higher amplitude tremor. Amounts of lava effusion and ash emission have also fluctuated slightly throughout the week, until this morning when ash production and lava fountaining have intensified.
The ash plume associated with the current level of unrest is moving in a southeasterly direction and has resulted in trace amounts of ash fall on areas downwind of the volcano including Perryville. Trace amounts of ash fall on other communities southeast of the volcano, including Chignik Bay, Chignik Lagoon, and Chignik Lake is possible. Ash fall amounts are not expected to be significant and likely will be less than 1/16 inch, although areas within 1-2 miles of the intracaldera cone could receive thicker amounts of ash fall. Information about volcanic ash and its potential effects can be found on the AVO web page (www.avo.alaska.edu).
AVO is monitoring the volcano closely and will provide additional information about the ongoing eruption as the situation warrants.
Aerial view of the eruption at Veniaminof's intracaldera cone, August 18, 2013. Image courtesy of AVO/USGS. Photographer: McGimsey, Game
Mount Veniaminof volcano is an andesitic stratovolcano with an ice-filled 10-km diameter summit caldera located on the Alaska Peninsula, 775 km (480 mi) southwest of Anchorage and 35 km (22 mi) north of Perryville. Veniaminof is one of the largest (~ 300 km3) and most active volcanic centers in the Aleutian Arc and has erupted at least 13 times in the past 200 years. Recent significant eruptions of the volcano occurred in 1993-95 and 2005. Both were moderate Strombolian eruptions producing intermittent low-level jets of incandescent lava fragments, and low-level emissions of steam and ash from the main intracaldera cone. During the 1993-95 activity, a small lava flow was extruded into the summit caldera ice field producing an ice pit. Minor ash-producing explosions occurred in 2002, 2004, early 2005, November 2006, and February 2008. Previous historical eruptions have produced ash plumes that reached 6,000 m (20,000 ft) above sea level and ash fallout that blanketed areas within about 40 km (25 mi) of the volcano.
Aviation Color Code - ORANGE
Volcano Alert Level - WATCH
Featured image: Aerial view of the eruption at Veniaminof's intracaldera cone, August 18, 2013. This cone rises about 1000 feet above the surrounding icefield. It has been intermittently erupting lava, ash and steam since June 13, 2013. This photo shows the incandescent, orange stream of molten lava emerging from the active cone. Steam billows from the pit at the base of the cone where the lava encounters and melts ice and snow. A small, ash-rich plume rises just above the vent producing a diffuse ash cloud that drifts downwind. In the foreground, round white patches probably represent ballistic impact craters. Photo taken by Game McGimsey, AVO/USGS. This overflight of Veniaminof was co-sponsored by the National Geographic Society.
Image courtesy of AVO/USGS. Photographer: McGimsey, Game
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