Global Volcanism Program | Image GVP-01028
Submarine eruptions within Krakatau caldera were first observed in December 1927 and an ephemeral island appeared the following month. This 1929 view shows an ash-rich cock’s tail jet typical of shallow submarine explosions. Material ejected by earlier eruptions forms an island visible to the left. By August 1930 Anak Krakatau became a permanent island.
Photo by C.E. Stehn, 1929 (courtesy Volcanological Survey of Indonesia).