AVO reported that seismic data indicated that the eruption of lava from the cone in Veniaminof’s ice-filled summit caldera possibly paused on 6 December. Satellite data acquired on 10 December suggested lava effusion had stopped, though weak explosive activity from the vent possibly still occurred. No eruptive activity was evident in satellite and webcam images on the morning of 13 December. However, beginning in the afternoon intermittent tremor appeared and gradually became continuous. A plume, possibly containing ash, and elevated surface temperatures were identified in satellite and webcam images. A strong thermal anomaly was visible in satellite and webcam data during 14-15 December, and together with an eruption plume, was consistent with lava fountaining at the summit vent. By 16 December a lava flow was erupting from the vent. The Aviation Color Code remained at Orange (the second highest level on a four-color scale) and the Volcano Alert Level remained at Watch (the second highest level on a four-level scale).

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)