Video was taken during a VolcanoDiscovery expedition to Krakatau from 13-20 Oct 2018. In the afternoon of 17 Oct, a particularly violent explosion occurred as lateral blast that excavated a pit crater beneath the southern lid of the crater, at the same location the September lava flow had overspilled from the crater. By 19 Oct, this new pit had merged with the main crater, enlarging it.
Also Read: USGS Research Publishes Updated List Of U.S. Volcanos With Highest Danger To Erupt