Volcanic ash from Mount Anak Krakatau blankets parts of Java and Sumatra, disrupting travel and raising health concerns

Indonesia's Geological Agency reported that a 25-hour continuous eruption of Mount Anak Krakatau ended on Sunday, but smaller intermittent eruptions have continued and the likelihood of further eruptions "remains high." A three-kilometre exclusion zone remains in place around the volcano.

Jakarta's main Soekarno-Hatta International Airport and four other airports reopened on Tuesday after winds cleared ash from surrounding areas. According to InJourney Airports, which manages commercial airports across Indonesia, nearly 3,000 flights were cancelled or delayed as a result of the ash.

Ash has also disrupted communities in Lampung province, about 75 kilometres north-east of the volcano. Elizabeth Amelia, a resident of the city of Bandar Lampung, said she was concerned about the health of her two-year-old child and her 63-year-old mother. "I'm worried it could affect their breathing. If it's inhaled too much, it could cause a respiratory infection," she said.

Amelia said her daughter and mother had not gone outside since the ash fall began, while she and her husband wore masks to go to work. She described the ash as "truly intense," noting that car windows were "completely covered in ash, absolutely caked in it, not just a light dusting." She said the ash fall felt worse than in 2018, when volcanic activity at Mount Anak Krakatau triggered an undersea landslide and tsunami in the Sunda Strait that killed at least 430 people, injured 1,485, and displaced about 20,000. Living less than one kilometre from the coast, Amelia said she is also anxious about the risk of another tsunami.

Why This Matters

Health risks: Volcanic ash can cause respiratory infections, particularly for vulnerable groups such as children and the elderly. Residents in affected areas are already limiting outdoor exposure.
Travel chaos: The disruption to nearly 3,000 flights and more than 340,000 travellers, including Australians, highlights the vulnerability of air travel to volcanic ash, with potential economic ripple effects.
Ongoing threat: The Geological Agency's warning that further eruptions remain likely means communities and aviation authorities must remain on alert, and the exclusion zone may stay in place for an extended period.

Background

Mount Anak Krakatau, or "Child of Krakatau," is a volcanic island in the Sunda Strait between Java and Sumatra. It emerged from the caldera of the famous Krakatau volcano, whose 1883 eruption was one of the deadliest in history. In December 2018, a partial collapse of Anak Krakatau triggered an undersea landslide and tsunami that devastated coastal areas of Java and Sumatra, killing hundreds. The current eruption has not produced a tsunami, but the proximity of communities to the coast has heightened anxiety.

Key Perspectives

Local residents: Those living near the volcano, such as Elizabeth Amelia in Lampung, face immediate health risks from ash inhalation and psychological stress from the memory of the 2018 disaster. Many are choosing to stay indoors and wear masks when going out. Travel and aviation authorities: Airports in Jakarta and other cities have reopened after ash cleared, but the ongoing eruption risk means further closures are possible. The scale of disruption — nearly 3,000 flights — underscores the challenge of managing airspace near active volcanoes. Indonesian Geological Agency: The agency has warned that the likelihood of further eruptions remains high, and the exclusion zone is likely to remain in place. It continues to monitor seismic activity and ash dispersal.

What to Watch

Further eruption activity: Whether the volcano produces larger eruptions or more sustained ash plumes that could again close airports and affect communities.
Wind patterns: The direction of winds will determine which areas receive ash fall, potentially affecting more regions of Java and Sumatra.
Tsunami risk: Any sign of volcanic flank collapse could trigger a tsunami, especially given the 2018 precedent. Monitoring of the volcano's structural stability is critical.

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