The 2026 Anak Krakatau eruption was a series of volcanic events in the form of a continuous eruption phase and lava fountain that occurred in Sunda Strait on September 4 to 6, 2026. This eruption produced a column of volcanic ash that rose high into the atmosphere, causing an acoustic boom phenomenon that was heard in several areas of the islands of Java and Sumatra, and causing the temporary closure of a number of airports in Indonesia.
Background
Following the eruption and partial collapse of the volcano that triggered the Sunda Strait tsunami on December 22, 2018, Mount Anak Krakatau entered a phase of reconstruction, or morphological restructuring, through a series of small-scale eruptions until December 16, 2023. After a lull, the volcano experienced increased volcanic activity again on July 2, 2026, prompting the Center for Volcanology and Geological Hazard Mitigation (PVMBG) to raise its activity status to Level III (Alert). The eruptions during this period were predominantly Strombolian, spewing out incandescent rock and volcanic ash.
Chronology of the eruption
September 4, 2026: Continuous increases in eruptive activity were observed at 11:07 PM WIB (Western Indonesian Time). The eruption was accompanied by rumbling and fountain-like eruptions of incandescent lava. The Soekarno-Hatta Meteorological Station immediately issued the first Significant Meteorological Information (SIGMET) early navigation warning at 11:23 PM WIB.
September 5, 2026: The eruption continued throughout the early morning and into the evening. The volcanic ash column was recorded reaching a height of up to 50,000 feet (approximately 15,000 meters above sea level). The ash was distributed in two layers of the atmosphere, carried by the wind in various directions. By the afternoon, the intensity of the eruption was reported to have begun to gradually decrease.
September 6, 2026: The Geological Agency of the Ministry of Energy and Mineral Resources (ESDM) confirmed that the series of continuous lava eruptions officially stopped at 00.04 WIB.
Impact
Volcanic Ash Distribution and Health
Himawari-9 satellite imagery and monitoring data from the Meteorology, Climatology, and Geophysics Agency (BMKG) identified volcanic ash distribution reaching at least six provinces on the islands of Java and Sumatra, including Lampung, Banten, Jakarta, West Java, Bengkulu, and West Sumatra.
Impact
Volcanic Ash Distribution and Health
Himawari-9 satellite imagery and monitoring data from the Meteorology, Climatology, and Geophysics Agency (BMKG) identified volcanic ash distribution reaching at least six provinces on the islands of Java and Sumatra, including Lampung, Banten, Jakarta, West Java, Bengkulu, and West Sumatra.
A layer of surface ash up to a height of 20,000 feet spread to the southeast, south, and northeast, covering parts of Banten, West Java, and DKI Jakarta.
The ash layer at an altitude of up to 50,000 feet moved southwest and northwest, crossing the coastal areas of the Sunda Strait, Lampung, Bengkulu, and the Indian Ocean.
Exposure to volcanic ash particles has triggered respiratory complaints, eye irritation, and throat discomfort for residents in affected areas, such as Bandar Lampung City, Pesawaran Regency, Serang Regency, Bogor City, Sukabumi Regency, and DKI Jakarta. The Bandar Lampung City Government responded to the situation by spraying water on main roads, while the Ministry of Health urged people to reduce outdoor activities and prepared medical equipment in the form of nebulizers and oxygen concentrators at health facilities.
Aviation
To ensure the safety of international and domestic air travel due to the high concentration of volcanic ash, the Indonesian Air Navigation Service Provider (AirNav Indonesia) issued several Notices to Airmen (NOTAMs). This coordination between aviation authorities resulted in the temporary closure of several airports, including:
Soekarno-Hatta International Airport (Tangerang, Banten)
Halim Perdanakusuma International Airport (East Jakarta, DKI Jakarta)
Radin Inten II International Airport (South Lampung, Lampung)
Husein Sastranegara International Airport (Bandung, West Java)
Budiarto Airport (Curug, Tangerang)
Pondok Cabe Airport (South Tangerang, Banten)
Potential for marine hazards and tsunamis
Based on the Geological Agency's evaluation and observations by 20 sea level sensors (tsunami gauges) and High-Frequency Radar Array technology by the Meteorology, Climatology, and Geophysics Agency (BMKG), the probability of a tsunami is low (below 40 percent). The cone of Mount Anak Krakatau, which re-formed after 2018, remains relatively small, thus not showing the potential for a large-scale collapse capable of triggering extreme sea waves.
This eruptive activity has also attracted international attention. The Japan Meteorological Agency (JMA) is monitoring atmospheric pressure dynamics and the potential for a tsunami across the region, citing the precedent of the 2022 eruption of Mount Hunga Tonga–Hunga Haʻapai.
Controversy over the Boom Phenomenon
Concurrently with the eruption phase on September 4–5, 2026, repeated booming sounds and vibrations of glass/doors were reported by residents in various areas of West Java (including Greater Bandung), Banten, and Lampung.
The Center for Volcanology and Geological Hazard Mitigation (PVMBG): Suspects that the booms are directly related to the eruptive activity of Mount Anak Krakatau. Similar phenomena were recorded during the eruption of Mount Anak Krakatau in April 2020 and the 2014 eruption of Mount Kelud, where low-frequency acoustic waves can propagate hundreds of kilometers under certain atmospheric conditions.
The Meteorology, Climatology, and Geophysics Agency (BMKG): Stated that it could not yet confirm that the eruption of Anak Krakatau was the primary cause of the booming sounds in Greater Bandung. Analysis of wind direction at the time of the incident (southeast to west) and the geographical distance were deemed physically less conducive to sound propagation reaching Bandung. BMKG classifies the phenomenon as a skyquake puzzle that still requires further multidisciplinary investigation.
Source: https://id.wikipedia.org/wiki/Letusan_Anak_Krakatau_2026
.png)