Anak Krakatau eruption log: every discrete eruption since 4 September, including a third one this morning

Safety & SecurityIssued: September 8, 2026

Our other articles on this crisis track airport closures and reopenings (see our separate pieces on the Jakarta-area closures and reopening, ashfall reaching Jakarta city, and the health-ministry response) — those are largely resolved now that Soekarno-Hatta and most other airports have reopened. This entry is a standing, dedicated log of the volcano's own activity: every discrete eruption event Badan Geologi/PVMBG has recorded since the continuous eruption began on 4 September, with seismograph amplitude and duration for each. Anak Krakatau has remained at Level III (Siaga) throughout, unchanged since 2 July 2026, and a third distinct eruption was recorded this morning (8 September) after two earlier ones — bringing the confirmed discrete-eruption count since 6 September to six. We will keep updating this log independently of the airport-status articles, since the volcano itself remains active even as flight operations return to normal.

Timeline

2 Jul 2026
Badan Geologi / PVMBG raises Anak Krakatau to Level III (Siaga) and sets a 3 km exclusion radius around the crater for residents, visitors, fishermen and climbers. More than 240 eruptions are recorded between then and 5 September.
Fri 4 Sep, 23:07 WIB
A continuous eruption begins, with booms and rumbling audible from the Pasauran observation post in Serang and reported across Banten, Lampung and West Java. The seismograph records a single eruption tremor of 70 mm amplitude lasting 21,600 seconds (six hours) — the strongest activity since the alert was raised. PVMBG interprets it as a lava fountain producing lava flows.
Sat 5 Sep, 00:50 WIB (02:50 JST)
The Japan Meteorological Agency reports a large eruption; Himawari-9 satellite imagery puts the plume at roughly 15 km (48,000–50,000 ft) above sea level.
Sun 6 Sep, 00:04 WIB
The continuous eruption ends, roughly 25 hours after it began. Badan Geologi confirms activity has "decreased again" but keeps the alert at Level III, saying monitoring continues given the potential for further eruptions.
Sun 6 Sep, 03:53 WIB
The first discrete eruption after the continuous episode: maximum amplitude 46 mm, duration 30 seconds. The ash column is not observed.
Sun 6 Sep, 07:10 WIB
A second discrete eruption: maximum amplitude 50 mm, duration 16 seconds. Again the ash column is not observed.
Sun 6 Sep, 20:23 WIB
A third discrete eruption: maximum amplitude 58 mm, duration roughly 44 seconds. Badan Geologi's own recap the next morning describes these three as strombolian eruptions producing black ash columns of unrecorded height.
Mon 7 Sep, 06:00 WIB recap
Badan Geologi's instrumental summary for 6–7 September logs 3 eruption earthquakes, 9 explosion earthquakes, 93 low-frequency earthquakes, 98 hybrid/multi-phase earthquakes, 4 continuous tremors and 1 shallow volcanic earthquake — a busy seismic day even without a further discrete eruption being separately announced. Visual observation is variable (clear to overcast, weak-to-moderate winds from the north/northwest), and the alert stays at Level III.
Tue 8 Sep, 05:08 WIB
The first eruption of the day: maximum amplitude 47 mm, duration 15 seconds. The column is not visually observed — fog is covering the volcano at the time, per the Anak Krakatau monitoring post in South Lampung.
Tue 8 Sep, 05:34 WIB
A second eruption follows about 26 minutes later: maximum amplitude 44 mm, duration 10 seconds.
Tue 8 Sep, 07:49 WIB
A third eruption of the morning: maximum amplitude 48 mm, duration 19 seconds — this time with an observed ash column reaching roughly 7,000 ft (2.1 km), moving south-southwest toward northwestern Banten and the northwestern Indian Ocean. BPBD Lampung issues an eruption-detection alert. This brings the confirmed discrete-eruption count since 6 September to six.
Tue 8 Sep, ~12:00 WIB
The latest forecast has the news turning more favourable: BMKG's ash-dispersal forecast now has the plume moving away from Indonesian territory rather than over it, a reversal from the westward-expansion forecasts earlier in the week. Badan Geologi's hazard assessment still flags an elevated probability of further eruptions in coming days, with the main threats being ejected incandescent rock and heavy ashfall near the crater, and renewed lava flow if a continuous eruption resumes.

Key points

Volcano status: unchanged at Level III (Siaga) since 2 July 2026, with a standing 3 km exclusion radius around the crater for residents, visitors, fishermen and climbers.
This is a dedicated eruption-activity log, separate from our articles on airport closures/reopening, Jakarta-city ashfall, and the health-ministry response — check those for operational and health guidance rather than this page.
Tsunami: PVMBG has repeatedly stated the cone rebuilt since the December 2018 collapse is too small to trigger a tsunami-scale collapse, and asks the public not to be swayed by rumours. Treat any viral tsunami warning as unverified unless it comes from BMKG or Badan Geologi directly.
Hazard outlook: Badan Geologi's own assessment (as of 8 September) still rates the probability of further eruptions as elevated, with the main risks being ejected incandescent rock and heavy ashfall near the crater, and renewed lava flow if a continuous eruption resumes.
A late-morning 8 September BMKG forecast has ash dispersal now moving away from Indonesian territory, a reversal from the westward-expansion forecasts seen earlier in the week — a positive sign, though not a declaration that activity has ended.

What this means for your Indonesian entity

This log is a standing reference for one question: is the volcano still active? Keep it bookmarked separately from operational updates. As of writing, airports have largely reopened (see our separate article) even though the volcano itself continues to erupt intermittently — the two are not the same signal, and a new eruption does not automatically mean a new closure. If your staff or operations are in Banten, Lampung, or coastal West Java, the practical trigger for action remains the same as before: watch for fresh ashfall or mask advisories from BPBD, not the eruption count itself. We will add new eruptions to this timeline as Badan Geologi confirms them, and will note here if the alert level itself changes from Level III.

Sources

This page summarises publicly available information for orientation. It is not tax, legal, or accounting advice, and regulations change. Verify against the linked primary sources and contact us before acting on anything here.

この記事の日本語版を読む

Update: Soekarno-Hatta and four other airports reopen overnight — Garuda resumes Jakarta flights in phases from 8 September All news

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