Alaska Volcano Observatory (AVO) reported on June 13, 2013 that an eruption at the intracaldera cone is likely underway at Veniaminof volcano, Alaska as determined from satellite observation of elevated surface temperatures at 13:25 UTC. This prompted AVO to raise the Aviation Color Code to ORANGE and Volcano Alert Level to WATCH. Seismic tremor continues and is indicative of low-level effusive activity and small explosions. However no ash plumes have been observed on the morning of June 13, 2013, although clouds have obscured web camera views of the summit. According to AVO, any low-level plume produced would drift to the northwest based on predicted wind trajectories.
Northwest view from Perrywille's FAA aviation camera shows calm Veniaminof on June 11, 2013 (left) and ash plume rising above the volcano on June 13, 2013 (Credit: FAA/Avcams)
AVO has been monitoring Veniaminof closely since elevated levels of seismicity became persistent on June 8, 2013. Steam plumes issuing from the intracaldera cone have been observed in web camera views since then, but so far no ash emissions have been confirmed.
NOAA ARL 24 hour Ash Trajectory Forecast (Credit: NOAA/ARL)
Recent eruptions of Veniaminof volcano have all occurred from vents located on the intracaldera cone and were characterized by brief bursts of ash emission and small explosions. AVO points ash plumes associated with this type of activity are typically diffuse and generally do not reach more than 20,000 feet above sea level. Ash fallout is typically limited to the flanks of the volcano, and minor emissions of steam and ash may persist for for weeks to months.
The last episode of more energetic activity occurred in 1993-94 when an ash plume rose to about 18,000 feet above sea level and small lava flows poured onto glacier ice around the intracaldera cone. An eruption in 1983-84 produced an ash plume that reached about 25,000 feet above sea level.
Seismic recording from Veniaminof on June 13, 2013 (Station: VNHG_EHZ_AV)
Massive Veniaminof volcano, one of the highest and largest volcanoes on the Alaska Peninsula, is truncated by a steep-walled, 8 x 11 km, glacier-filled caldera that formed around 3700 years ago. The caldera rim is up to 520 m high on the north, is deeply notched on the west by Cone Glacier, and is covered by an ice sheet on the south. Post-caldera vents are located along a NW-SE zone bisecting the caldera that extends 55 km from near the Bering Sea coast, across the caldera, and down the Pacific flank. Historical eruptions probably all originated from the westernmost and most prominent of two intra-caldera cones, which reaches an elevation of 2156 m and rises about 300 m above the surrounding icefield. The other cone is larger, and has a summit crater or caldera that may reach 2.5 km in diameter, but is more subdued and barely rises above the glacier surface.
Featured image: ASTER satelite image captured steam plume emitting from the active intracaldera cone at Veniaminof volcano on March 4, 2008 (Image processed by AVO/USGS. Image data courtesy of NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team)