Anak Krakatau's 25-Hour Eruption Grounds Flights Across Indonesia's Capital Region
Ash closed eight airports, including Jakarta's main hub, and sent schools online in four provinces. Volcanologists warn more eruptions are likely at a volcano whose 2018 collapse caused a deadly tsunami.
Anak Krakatau, the volcano that rose out of the sea between Java and Sumatra, erupted without pause for about 25 hours over the first weekend of September, throwing up a fountain of lava and a blast heard roughly 700 kilometres away. The eruption itself caused no reported casualties. Its ash did something almost as disruptive: it shut the skies over Indonesia's capital.
Eight airports suspended operations after ash was detected in their airspace, among them Soekarno-Hatta, Jakarta's main international gateway and one of the busiest airports in South-East Asia. At the four airports run by the state operator InJourney alone, around 2,300 flights were disrupted and more than 268,000 passengers were affected.
What happened
The continuous phase of the eruption ended on Sunday 6 September, Indonesia's Geological Agency said, but the volcano stayed restless into the following day, with intermittent moderate blasts, dark ash plumes and small local earthquakes. Airports at Jakarta's Soekarno-Hatta and Halim Perdanakusuma, Bandung's Husein Sastranegara and Lampung's Radin Inten were among those kept closed until Monday evening while the ash cleared.
Beyond aviation, the authorities told schools in Jakarta, West Java, Banten and Lampung to move lessons online, keeping children indoors while ash fell across a region home to tens of millions of people.
The agency has not declared the danger over. Its head, Lana Saria, said the likelihood of further eruptions in the coming days "remains high", and warned of volcanic bombs, heavy ashfall and possible lava flows near the island.
The context: a volcano with a deadly record
Anak Krakatau, whose name means "child of Krakatoa", grew from the caldera left by the catastrophic 1883 eruption. It has a recent history that makes officials cautious. In December 2018, part of its flank collapsed into the sea and set off a tsunami that killed at least 430 people along the coasts of the Sunda Strait, with almost no warning.
Indonesia sits on the Pacific Ring of Fire and has more than 120 active volcanoes. Eruptions that close regional airports are not unusual. An eruption that grounds flights at the country's busiest hub, and forces a partial shutdown of the capital's schools, is a different order of disruption.
Why it matters
The weekend showed how exposed a large economy can be to a single volcano sitting 150 kilometres from its capital. Jakarta's airports are the centre of Indonesia's domestic network, which ties together an archipelago where air travel is often the only practical way to move between islands. When they close, the effect spreads to cities thousands of kilometres from the ash.
There is also a safety question that goes beyond flights. The 2018 disaster showed that the greatest danger from Anak Krakatau may not be the eruption itself but what it does to the sea. Monitoring of the volcano's slopes and the coastal warning systems around the strait were strengthened after that event, and this eruption has put them under renewed scrutiny.
Key points
- Anak Krakatau erupted continuously for about 25 hours, ending on 6 September, with activity continuing afterwards.
- Eight airports, including Jakarta's Soekarno-Hatta, halted operations after ash was detected.
- Around 2,300 flights and more than 268,000 passengers were affected at four state-run airports.
- Schools in four provinces, including the capital, switched to online learning.
- The Geological Agency says the chance of further eruptions remains high.
What comes next
Flights resumed once the ash cleared, but airlines and passengers face a period in which schedules depend on the wind and the volcano's mood. If fresh eruptions push ash towards Java again, the closures could return at short notice.
For the authorities, the priority is watching for any sign of instability in the volcano's structure, the kind of change that preceded the 2018 collapse. For travellers and businesses, the lesson of the week is simpler: in Indonesia, the busiest airports in the region can be closed not by weather or strikes, but by an island in the sea.
Image: Annamaria Luongo via Wikimedia Commons, CC BY 2.0