Mount Anak Krakatau Erupts Overnight, Spewing Lava Fountains

Mount Anak Krakatau kept erupting into Saturday morning, its plume glowing bright red above the Sunda Strait while rumbling sounds reached the Krakatau Pasauran monitoring post. The Geological Agency said the eruption was still underway at 4:40 a.m. Western Indonesian Time on Sept. 5.

The height of the eruption column could not be observed, but the volcano spewed incandescent rocks and ash. The activity began with eruptions recorded by seismographs from Friday morning, including events at 4:11, 4:19, 4:28 and 5:46 a.m. The first recorded eruption had a maximum amplitude of 33 millimeters and lasted 14 seconds. Later eruptions showed greater amplitude and slightly longer durations.

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As of today, September 5, 2026, at 4:40 a.m. Western Indonesian Time, the eruption is still ongoing, and rumbling can still be heard from the Krakatau Pasauran PGA Post.

After a pause, another series began at 10:03 p.m. Friday. Available data recorded six eruptions through 12:01 a.m. Saturday. The Geological Agency described the phenomenon as resembling a “lava fountain” that produces lava flows, while noting that continuous eruptions lasting several hours are common.

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This eruption phenomenon resembles a 'lava fountain' that produces lava flows.

Residents reported booming sounds and vibrations in parts of West Java, Banten and Lampung. The agency said the reports appeared to coincide with Anak Krakatau’s activity. The volcano has remained at Alert Level III since July 2.

The agency also said Anak Krakatau’s growth after the Dec. 22, 2018, eruption remained relatively small. “There is no potential for a collapse on a scale that could trigger a tsunami,” it said.

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There is no potential for a collapse on a scale that could trigger a tsunami.