Satellite imagery detects two new land formations near Indonesia's Anak Krakatau volcano
Indonesian authorities confirmed the emergence of two island-like land formations in the Sunda Strait after a September eruption expanded the Anak Krakatau volcano by 32.8 hectares.
Discovery and satellite confirmation
Indonesia's Center for Volcanology and Geological Hazard Mitigation (PVMBG) confirmed that two new land masses have emerged in the waters surrounding Anak Krakatau. The formations were identified through Sentinel Earth observation satellite imagery managed by the European Space Agency (ESA). Official measurements show that one formation lies 760 meters northwest of the volcano, while the other is situated 495 meters to the southwest. Both landmasses remain within one kilometer of the volcanic cone in the Sunda Strait between Java and Sumatra.
Rita Susilawati, a spokesperson for the volcanology agency, confirmed the findings during an official announcement following the satellite data review.
Based on the analysis of Sentinel imagery, two formations that resemble small islands can be seen around Anak Krakatau.
- Northwest formation
- 760 m
- Southwest formation
- 495 m
September eruption and physical expansion
The new features appeared after an eruption that began on 4 September 2026 and continued for approximately 25 hours. The intense volcanic discharge deposited substantial volumes of lava into the sea, increasing the land area of Anak Krakatau by 32.8 hectares (81 acres). The accompanying ash plumes disrupted aviation across the country, leading to the closure of several regional airports and the cancellation of hundreds of scheduled flights.
The volcanic event also resulted in the disappearance of eight people in the surrounding waters, including five journalists who were documenting the activity from a vessel. Nearly two weeks after the eruption started, a search volunteer operating an aerial drone spotted one of the landmasses by chance after filming ocean waves breaking over a dark, protruding surface.
- Anak Krakatau starts a 25-hour eruption that disrupts air traffic and leaves eight missing.
- A search volunteer operating a drone films a dark landmass emerging from the water.
- Indonesian volcanology officials announce satellite confirmation of two new island formations.
- Indonesia's Geology Agency reports Anak Krakatau grew by 32.8 hectares from lava flows.
Geological origin and structural durability
Experts from Indonesia's Geology Agency are preparing field investigations to determine the composition, elevation, and surface area of the two landmasses. Geologists currently do not know whether the formations are loose accumulations of ejected volcanic debris or newly established submarine volcanic vents. The alert level around Anak Krakatau remains elevated while monitoring stations track ongoing geological activity.
Scientists cautioned that the two features might not endure over time. Intense wave motion and marine erosion in the Sunda Strait could dismantle and submerge the deposits before they solidify. Susilawati pointed out that it is premature to classify these formations as permanent offspring of the volcanic island.
Historical patterns in the Sunda Strait
If the newly formed masses survive oceanic erosion, the development will represent the first time since 1930 that volcanic activity from Anak Krakatau has established new islands. Anak Krakatau, meaning "Child of Krakatoa", sits inside the caldera left by the 1883 eruption of Krakatoa, which generated tsunamis and caused an estimated 35,000 fatalities along the coasts of Java and Sumatra.
The emergence mirrors the early development of Anak Krakatau itself in the late 1920s. Initial signs of the volcanic island emerged from the sea in late 1927, and additional material surfaced in 1928 before ocean waves eroded the deposits below the waterline, preceding the creation of a permanent landmass by 1930.
