Eruption Intensity of Anak Krakatau Declines, Volcanic Ash Moving Away from Indonesia
The Meteorology, Climatology and Geophysics Agency (BMKG) has recorded a decline in the intensity of activity of Mount Anak Krakatau in the Sunda Strait. Volcanic ash from Anak Krakatau is also continuing to decrease.
Head of BMKG, Teuku Faisal Fathani, initially explained that the agency had carried out periodic paper tests at several points to complement satellite imagery monitoring and aviation meteorological data. As a result, eight airports that had been closed have been reopened after paper tests showed negative results for volcanic ash.
“The results of paper test observations as of 06:00 WIB state that the eight airports previously closed for operations have been declared free of volcanic ash exposure. BMKG continues to monitor the movement of the ash in real time so that all flights can proceed safely,” said Faisal, as quoted from the official BMKG website on Tuesday (8/9/2026).
The airports that have resumed operations are Soekarno-Hatta Airport, Halim Perdanakusuma Airport, Husein Sastranegara Airport, Budiarto Curug Airport, Pondok Cabe Airport, Taufiq Kiemas Airport, Radin Inten II Airport and Salakanagara Tanjung Lesung Airport.
Acting Deputy for Meteorology at BMKG, Andri Ramdhani, said the agency is also monitoring volcanic ash generally at altitudes of up to 7,000 feet (2.13 km). He said the volcanic ash is now moving towards the south-south-west, covering part of north-western Banten and the Indian Ocean north-west of Banten. The volcanic ash is moving at speeds of up to 18.5 km/h as of 09:00 WIB on 8 September 2026.
“Weather observations around GAK (Mount Anak Krakatau) and the waters of the Sunda Strait tend to be sunny to partly cloudy from morning until night,” said Andri.
Furthermore, Acting Deputy for Geophysics at BMKG, Ardhasena Sopaheluwakan, said monitoring through 20 tsunami gauges and the HF Radar Array in Carita and Tanjung Lesung showed no anomalies in sea surface waves. BMKG stated that the probability of a tsunami remains in the low category. BMKG estimates that wave heights around the Sunda Strait over the next seven days will range between 0.5 and 3 metres.
BMKG, referring to the latest information from PVMBG at 07:49 WIB, observed a new eruption at Anak Krakatau with a maximum amplitude of 48 mm and a duration of 19 seconds, categorised as a Strombolian or minor eruption. BMKG is also monitoring geomagnetic disturbances and lightning strikes caused by Anak Krakatau’s activity through earth magnet sensors and lightning detectors.
As a result, BMKG recorded minor geomagnetic disturbance activity and volcanic lightning strikes from 21:00 to 23:00 WIB last night. This activity indicates a decline in intensity compared to previous days.
BMKG, together with the National Disaster Management Agency (BNPB), the Ministry of Transportation and relevant parties, is also continuing weather modification operations (OMC) which have been carried out since 7 September 2026. Deputy for Weather Modification at BMKG, Tri Handoko Seto, explained that the OMC team is applying rain cloud seeding methods as well as watermist spraying using two Cessna Caravan aircraft from the Pondok Cabe and Halim Perdanakusuma Airport posts.
“To date, OMC has carried out five flight sorties: one sortie using NaCl powder seeding material, one sortie with liquid CaCl2 and three sorties using spraying/watermist. Operations will continue in line with atmospheric conditions and the distribution of volcanic ash, so that the concentration of ash in the air is expected to keep decreasing and atmospheric conditions gradually become cleaner,” explained Seto.
BMKG urged the public to remain alert and calm regarding the impact of the Anak Krakatau eruption. People in areas exposed to volcanic ash distribution are advised to pay attention to their health by limiting outdoor activities. Residents carrying out activities outside the home are advised to always wear masks and goggles.