AVO reported that the eruption at Veniaminof continued during 9-16 March. Ash emissions rose to 2.1-3 km (7,000-10,000 ft) a.s.l. and drifted 200 km NE and SE during 9-10 March. Explosions and ash emissions declined to lower levels the rest of the week, though new ash deposits within the caldera, and as far as 10 km SE, were sometimes identified in satellite images. Lava continued to effuse under the intra-caldera glacier in an area on the flank about 1 km E of the cone’s summit. Elevated surface temperatures over this area were identified in a satellite images during most days, along with steam plumes and a broadening collapse pit in the ice from melting around the eruption site. Data from local seismic stations were back online by 12 March and showed elevated seismicity and tremor through 15 March. Steam-and-has plumes were identified in satellite images during 15-16 March. The Volcano Alert Level remained at Watch and the Aviation Color Code remained at Orange.

Geological Summary. Veniaminof, on the Alaska Peninsula, is truncated by a steep-walled, 8 x 11 km, glacier-filled caldera that formed around 3,700 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 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.

Source: US Geological Survey Alaska Volcano Observatory (AVO)