Anak Krakatau eruption forms two new islands, expands volcano by 33 hectares

October 3, 2026 at 05:31 PM2 min

This digest was compiled by AI from multiple sources — links to the originals are below.

A powerful eruption of Indonesia's Anak Krakatau volcano from September 4 to 6 formed two new island-like landmasses and expanded the volcano's area by about 33 hectares. The new formations were detected in satellite images and confirmed by sailors. The eruption also disrupted air traffic, with nearly 3,000 flights canceled, delayed, or diverted.

Key Facts

The eruption lasted from September 4 to 6, with an ash plume rising to approximately 15 kilometers.
One new island is located about 760 meters northwest of the volcano, and the other about 495 meters southeast.
The volcano's area increased by approximately 32.8 hectares, reaching about 341.5 hectares.
Nearly 3,000 flights were canceled, delayed, or diverted, affecting more than 340,000 passengers.
Eight airports, including those in the Jakarta area, were temporarily closed.

New Land Formations

Satellite images after the eruption revealed two new island-like landmasses near Anak Krakatau. One formation is located approximately 760 meters northwest of the volcano, while the other is roughly 495 meters southeast. Their appearance was also confirmed by observations from sailors and volunteers who photographed the changed coastline. Experts have not yet established the exact mechanism behind the formation of the new land areas. One theory suggests they formed from an underwater eruption, with lava and volcanic materials accumulating on the seabed until rising above the water's surface.

Volcano Expansion and Eruption Impact

The September eruption changed the shoreline of Anak Krakatau itself, increasing the island's area by approximately 32.8 hectares to about 341.5 hectares. During the active phase, the volcano emitted large volumes of ash and lava, with the ash plume rising to approximately 15 kilometers. The eruption caused serious disruptions to air traffic, with nearly 3,000 flights canceled, delayed, or diverted, affecting more than 340,000 passengers. Eight airports, including those in the Jakarta area, were temporarily closed. Subsequently, the volcano's activity began to decline, and the danger level was reduced from three to two.

Geological Assessment and Future Stability

Geologists note that it is still too early to say whether the new islands will remain permanent. If they consist primarily of loose volcanic material, waves and erosion could destroy them fairly quickly. If their foundation is solidified lava, the new land areas may endure. The Geological Agency of Indonesia stated that satellite images cannot determine the composition of the formations or confirm whether they are linked to new volcanic vents. Residents and tourists are prohibited from approaching the main crater closer than two kilometers.