Last Updated on 26 minutes ago by TodayWhy Editorial
A volcano with one of history’s deadliest names is erupting again. Anak Krakatau, the island that rose from the crater of the catastrophic 1883 Krakatoa eruption, has been sending lava fountains and ash 50,000 feet into the sky since September 4, 2026, grounding hundreds of thousands of travelers across Indonesia. Why did Anak Krakatau erupt now, why does its connection to Krakatoa matter, and why isn’t there a tsunami warning despite the volcano’s history? Here’s what’s known.
What Happened at Anak Krakatau?
Anak Krakatau, whose name means “child of Krakatau,” began erupting late on Friday, September 4, 2026, producing lava fountains and booming sounds that Indonesian authorities said could be heard up to 700 kilometers (435 miles) away. Ash was recorded as high as 20,000 feet on the Java side of the volcano and up to 50,000 feet on the Sumatra side, according to Al Jazeera’s reporting. Two additional eruptions were recorded on Sunday alone. As of Monday, Indonesia’s geology agency warned the probability of further eruptions remained high.
The volcano sits in the Sunda Strait, the narrow waterway separating the islands of Java and Sumatra, administratively part of South Lampung Regency in Lampung province. It remains at Alert Level III, the second-highest tier on Indonesia’s four-level volcanic warning scale, indicating an ongoing supply of magma and gas beneath the surface.
Why Did Anak Krakatau Erupt?
Anak Krakatau sits directly within the Pacific Ring of Fire, the horseshoe-shaped chain of fault lines and volcanoes circling the Pacific Ocean where the majority of the world’s earthquakes and eruptions occur. Indonesia alone straddles this zone with roughly 130 active volcanoes, a consequence of several tectonic plates grinding against and sliding beneath one another along the archipelago. That constant subduction feeds magma upward, and Anak Krakatau has been doing exactly this, repeatedly, since it first emerged from the sea a century ago: officials describe it as having an ongoing, active magma supply rather than behaving as a single, isolated event.
This pattern of frequent, recurring activity distinguishes Anak Krakatau from volcanoes that erupt rarely after long periods of dormancy. Because magma continues feeding the system from below, monitoring agencies treat individual eruptive episodes less as isolated surprises and more as data points in an ongoing process, which is part of why Indonesia’s geology agency can meaningfully assess probability of further activity rather than simply waiting to see what happens next.
Why Does Anak Krakatau’s Connection to the 1883 Disaster Matter?
Anak Krakatau literally rose from the ashes of catastrophe. It emerged from the sea in the 1920s, growing inside the caldera left behind by the original Krakatoa’s 1883 eruption, one of the deadliest and most destructive volcanic events ever recorded, which killed more than 30,000 people, most from the tsunamis it triggered rather than the eruption itself. That history is precisely why any fresh activity from Anak Krakatau draws intense global attention: it is, quite literally, still growing out of one of the most infamous natural disasters in recorded history, in the same strait, decades later.
Why Are So Many Flights Affected?
Eight airports, including Jakarta’s main international gateway, Soekarno-Hatta, halted operations after ash was detected in their airspace. By Monday, a total of 1,558 flights had been delayed or cancelled across the affected airports, more than 900 of them at Soekarno-Hatta alone, leaving more than 270,000 passengers stranded, according to Indonesia’s Transport Ministry. Volcanic ash is uniquely hazardous to aircraft: it can melt inside a jet engine’s combustion chamber and re-solidify on turbine blades, and it drastically reduces visibility, which is why airlines ground flights rather than attempt to fly through or around a plume, as IQAir’s tracking summary of the eruption noted. Airports in cities including Semarang and Surabaya were prepared as landing alternatives, and Jakarta closed schools, shifting classes online.
Why Isn’t There a Tsunami Warning This Time?
Indonesia’s disaster mitigation agency, BNPB, said there was no imminent tsunami risk from this eruption specifically. That reassurance carries real weight given the volcano’s track record: a 2018 eruption triggered a partial collapse of Anak Krakatau’s crater into the sea, generating a tsunami that killed more than 400 people along the coasts of Java and Sumatra with almost no warning, since the wave wasn’t caused by an earthquake, the trigger most tsunami detection systems are built to catch. Authorities have nonetheless barred vessels from a three-kilometer exclusion zone around the volcano and asked ships transiting the strait to stay alert. Separately, BNPB has proposed cloud-seeding operations, using aircraft to encourage rainfall that could help wash accumulated ash out of the air over affected regions.
What Happens Next?
With eruption probability still rated high and Alert Level III unchanged, the near-term outlook depends on whether Anak Krakatau’s activity tapers off or intensifies further. Airport authorities have warned that flight schedules may keep shifting as ash conditions change, and residents, fishermen, and tourists have been told to stay at least three kilometers from the active crater because of ash, hazardous gases, and flying debris. For now, officials are treating this as an ongoing, monitored event rather than one that has peaked. Volcanic ash drifting into the upper atmosphere can also produce strikingly vivid sunsets far from the eruption itself, the same basic light-scattering effect behind unusually red skies from wildfire smoke elsewhere in the world this year.
Frequently Asked Questions
Why did Anak Krakatau erupt?
Anak Krakatau sits on the Pacific Ring of Fire, where Indonesia’s tectonic plates constantly interact, feeding magma upward. The volcano has an ongoing, active magma supply and has erupted repeatedly since forming roughly a century ago.
Is Anak Krakatau the same as the volcano from 1883?
Not exactly. Anak Krakatau, meaning “child of Krakatau,” emerged in the 1920s inside the caldera left by the original Krakatoa’s catastrophic 1883 eruption, which killed more than 30,000 people.
How many flights have been affected by the eruption?
As of September 7, 2026, a total of 1,558 flights had been delayed or cancelled across eight affected airports, stranding more than 270,000 passengers, according to Indonesia’s Transport Ministry.
Is there a tsunami risk from the current eruption?
Indonesian authorities have said there is no imminent tsunami risk from this eruption. A 2018 eruption did trigger a deadly tsunami after a partial crater collapse, killing more than 400 people, which is why officials continue to monitor the volcano closely.
Which cities are affected by the volcanic ash?
Ash has spread across Jakarta, Bandung, Banten, Bengkulu, Lampung, South Lampung, and West Java, disrupting air travel, schools, and daily life in those regions.
Why is volcanic ash so dangerous for airplanes?
Volcanic ash can melt inside a jet engine and resolidify on turbine components, potentially causing engine failure, and it severely reduces visibility, which is why airlines ground flights rather than fly through an ash plume.