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Anak Krakatau Volcano | Dr John Seach
Last updated: January 2026
Sunda Strait, Indonesia
6.10 S, 105.42 E
summit elevation ~320 m (Anak Krakatau cone, variable)
Caldera complex with active cone
Anak Krakatau ("Child of Krakatau") is the active cone in the Krakatau caldera, infamous for the catastrophic 1883 eruption. Emerging in 1930, it has grown through frequent Strombolian and Vulcanian explosions, lava flows, and occasional paroxysms. The 2018 flank collapse triggered a deadly tsunami. Photos on this page are pre-2018 collapse; the island is now largely barren.
Warning: The volcano is highly unpredictable with sudden explosions, pyroclastic flows, and tsunami risk from collapses. A permanent exclusion zone (typically 2-5 km) is enforced; climbing is prohibited during elevated alerts.
Geology and Volcanology
The Krakatau complex is a caldera formed by the 1883 Plinian eruption in the Sunda Arc subduction zone. Anak Krakatau is a basaltic-andesitic cone built within the caldera, erupting gas-rich magma in persistent Strombolian activity with intermittent larger explosions and effusions. Prone to flank instability leading to collapses and tsunamis. Monitored by PVMBG with seismicity, deformation, gas, thermal, and satellite data.
Current Activity (January 2026)
Anak Krakatau is actively erupting (alert level 3/4). Frequent Strombolian explosions and ash plumes (up to 2-3 km altitude) continue from the summit crater, with gas-steam emissions and occasional incandescent ejecta. Seismic activity remains elevated. A 2-5 km exclusion zone is in place; maritime and aviation alerts active. No immediate tsunami threat, but monitoring by PVMBG is intensive due to collapse risk.
Anak Krakatau volcano photos by Dr John Seach (pre-2018 collapse)
Krakatau volcano eruption, September 2009 - Dr John Seach
Krakatau volcano eruption, September 2009 - Dr John Seach
Krakatau eruption 2009
Dr John Seach climbing Anak Krakatau east flank, April 2000
Warning: Climbing Anak Krakatau is currently prohibited and extremely dangerous.
Krakatau eruption 2009
Dr John Seach at summit of Anak Krakatau, April 2000
Warning: Climbing Anak Krakatau is currently prohibited and extremely dangerous.
Krakatau volcano 2009
Bomb crater, Krakatau volcano
Dr John Seach climbing Krakatau volcano
Warning: Climbing Anak Krakatau is currently prohibited and extremely dangerous.
Climbing Krakatau volcano
Dr John Seach at summit of Krakatau volcano, Indonesia
Warning: Climbing Anak Krakatau is currently prohibited and extremely dangerous.
Ongoing Eruption (2022-present)
Frequent Strombolian explosions and ash emissions continue into 2026, with variable intensity and alert levels.
2018-2020 Paroxysmal Phase
Major flank collapse and tsunami on 22 December 2018 (VEI 4); prolonged activity with high ash plumes.
2007-2012 Frequent Activity
Regular Strombolian-Vulcanian eruptions raising alert levels multiple times.
1883 Catastrophic Eruption
One of history's largest (VEI 6); global effects, tsunamis killed ~36,000.
Further reading
Ye, L. et al., 2020. The 22 December 2018 tsunami from flank collapse of Anak Krakatau. Science Advances, 6(3), eaaz1377.
Winchester, S., 2004. Krakatoa: The day the world exploded. Penguin UK.
Global Volcanism Program, 2026. Anak Krakatau reports. Smithsonian Institution.
Anak Krakatau Eruptions
2022-2026 (ongoing), 2018-2020 (major), 2007-2012, 2001, 2000, 1999, 1997, 1996, 1994-1995, 1992-1993, 1988, 1981, 1980, 1979, 1978, 1975, 1972-1973, 1969?, 1965?, 1959-1963, 1958-1959, 1955, 1953, 1952, 1950, 1949, 1946-1947, 1946, 1945, 1944, 1943, 1942, 1941, 1938-1940, 1937, 1936, 1935, 1932-1934, 1931-1932, 1927-1930 (pre-Anak), 1883 (caldera-forming), older historic