Veniaminof is a large stratovolcano that suffered a huge caldera-forming eruption about 3,700 years ago. The caldera is almost 6 miles (10 km) across and filled with ice and snow. All the recent eruptions have taken place from a cinder cone that pokes up through the ice in the caldera. Both the 1983-84 and June 1993-present eruption have consisted of fountaining at this cinder cone. Additionally, lava flows flow down the sides of the cone and onto the ice surface where they then melt their way down through to the bottom of the caldera and then a lake forms.