New Landmass Near Anak Krakatau: A New Eruption Center? - Tempo.co English
TEMPO.CO, Jakarta - Two new landmasses unexpectedly surfaced near Anak Krakatau Volcano following a sustained eruption in the Sunda Strait from September 4 to 6, 2026. Speculation has arisen that these features could signal the formation of new eruption centers, though further studies are required to confirm this.
"The Geological Agency still needs the latest data, analysis, and field verification once conditions allow," said Lana Saria, Head of the Geological Agency at the Ministry of Energy and Mineral Resources, in a statement on September 26, 2026.
Lana noted that reports regarding the two mounds or "islets" came from mariners and volunteers who navigated and photographed the waters around the volcano on September 22. Their presence was subsequently verified by Sentinel satellite imagery covering the Anak Krakatau sector.
"Sentinel satellite imagery reveals two island-like formations, one in the northwest sector roughly 760 meters off the coast and another in the southeast sector about 495 meters offshore," Lana stated.
Preliminary analysis by the Geological Agency attributes their emergence to Anak Krakatau's 25-hour non-stop eruption between September 4 and 6, 2026. Lana added that should these landmasses prove to be new eruption centers, it will assist in analyzing the volcano's ongoing processes.
"If field evaluation and verification confirm that volcanic materials have indeed emerged in both locations, this finding will assist the Geological Agency in understanding the ongoing eruption process and the change in volcanic material eruption points," Lana said.
However, Lana clarified that this discovery does not automatically imply that future eruptions will occur from these two locations. She stressed that activity assessments and public safety guidelines remain anchored in comprehensive monitoring data across the entire volcano.
Anak Krakatau Volcano was elevated to Level III (Alert) status on July 2, 2026. From that point through September 3, 2026, observers recorded a series of Strombolian eruptions hurling incandescent rocks and volcanic ash. A prolonged eruption then broke out on September 4, 2026, at 11:07 p.m. WIB, continuing uninterrupted for 25 hours before winding down on September 6 at 12:04 a.m. WIB.
Lana noted that the September 4–6 continuous eruption sent lava flows streaming toward the northwest-west-southwest sectors. "Sentinel satellite imagery analyzed on September 15, 2026, indicated that Anak Krakatau's landmass expanded by 32.8 hectares," she added, highlighting that an earlier analysis on August 8, 2026, measured the volcanic structure at 312.3 hectares.
Lana noted that activity at Anak Krakatau has since subsided, prompting the Geological Agency to downgrade its alert status. On September 21, 2026, at 6:30 p.m. WIB, the volcano's status was officially lowered from Level III (Siaga) to Level II (Waspada).
Meanwhile, Happy Christin Natalia, a Geological Engineering lecturer at the Lampung Institute of Technology (Itera), attributed the new landmasses to the accumulation of eruptive deposits. "These landmasses do not originate solely from the 2026 eruptions as the area is quite extensive," she told Tempo on September 25, 2026.
According to Christin, each eruption deposits volcanic debris into the sea, which ocean currents then transport and deposit at specific locations. Ocean currents driving this material movement represent one key mechanism behind the appearance of the small landmasses northwest and southeast of Anak Krakatau. "Furthermore, ejecta from the eruption does not merely settle on the slopes; it can also slide into the sea," she explained.
Christin agreed that determining whether these landmasses are new eruption sources requires further research, noting that satellite images should show thermal hotspots if active vents exist. "So, it cannot be determined for certain whether it is a new volcanic body or just a pile of materials; more in-depth research is needed," she said.
Similarly, the possibility that the landmasses were formed by lava emerging from underwater fissures must be evaluated through bathymetric mapping.
Christin noted that these unsolidified structures remain unstable. "Because the materials are not solid but loose, they can be carried by currents anywhere," she said, adding, "The island is like a sand dune that could disappear at any time."
Read: When Will Anak Krakatau Erupt Next? Here's What Experts Say
