Anak Krakatoa ash spreads toward Banten, West Java and Sumatra as residents urged to stay indoors

Volcanic ash from Anak Krakatoa was detected moving toward Banten, parts of West Java, Jakarta, Lampung and Bengkulu, prompting Indonesian authorities to urge residents in affected areas to stay indoors.

Lana Saria, head of the Geological Agency at the Energy and Mineral Resources Ministry, said the ash's direction and range depended heavily on winds at different altitudes. The height and duration of the eruption, along with the amount of material released, would also shape its spread.

She said information from the country's volcano-monitoring center, aviation notices, weather authorities and Himawari-9 satellite imagery showed ash moving toward the listed regions. The data includes the eruption's source, timing, ash-column height, color, intensity and movement, and is shared through the Volcano Observatory Notice for Aviation system.

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The direction and extent of ash dispersal can change within a relatively short time. Therefore, information about ash distribution needs to be continuously updated based on the latest meteorological conditions.

Aviation authorities use those notices to assess flight safety. Decisions about airport operations depend on actual ash conditions, forecasts and aviation safety standards. Saria warned that the potential impact could widen if the eruption column rises higher, the eruption lasts longer or winds carry ash toward flight paths and populated areas.

The Geological Agency said ash spread cannot be projected from a single eruption alone because wind direction and speed can change. It advised people in affected areas to avoid outdoor activity, follow official government information and wear masks to protect against volcanic ash.

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The potential for wider impacts will increase if the eruption column becomes higher, the eruption lasts longer, or winds carry ash toward flight paths and populated areas.