After declining late March-early April, eruptive activity continued through late April. On 12-15 April, Perryville residents observed a small continuous vapor cloud of variable volume above the intra-caldera cone. On the 16th, a similar cloud, but of constant volume, was observed. Between 1230 and 1400 on 17 April, a very dark continuous ash plume rose to more than 2 km altitude from the intra-caldera cone. On the 18th, a small vapor cloud of variable volume rose from the cone. No observations were made on the 19th-21st, and weather clouds obscured the volcano on the 22nd. On 23-24 April, Perryville residents again observed a small steam cloud that varied in volume. No incandescence was observed over the summit between 11 and 26 April; glow was last observed on 16 March.

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.

Information Contacts: M.E. Yount, USGS, Anchorage.