District and province authorities were warned three days before the start of the 7 October eruption that Kudriavy was unstable and could erupt soon. Ejections of gas and ash occurred at intervals of 1-2 minutes. Because of the strong winds, maximum altitude of ejections was 1,100 m. Night observations showed that intense ejections stopped at 0200 on 8 October. Aerial photograph of the N part of the Kudriavy crater at Medvezhia showing the locations of the upper camp and the new explosion crater W of the hot lava dome during 7-8 October 1999.
North is to the left.
Courtesy of G.S. Steinberg. No juvenile ash was identified, so the eruption was determined to be phreatic. Ejecta didn't fall more than 30-40 m from the new crater. The volume of erupted material was nearly 40,000-45,000 m 3 . The first phase of the eruption was over on 13 October.