This Week
in Fire

Indonesia supplied the week's clearest change in volcanic status. Sinabung's activity increased sharply at the end of August, prompting Badan Geologi to raise the volcano from Level II to Level III and triggering precautionary evacuations. Elsewhere, Kīlauea's summit reinflation strengthened enough for HVO to establish a new broad Episode 55 forecast window, Mayon recorded an abrupt rise in sulfur dioxide output, and Etna briefly returned to ash emission before the event stopped.

🇮🇩 Sinabung Level III · Renewed Eruption

Indonesia's Badan Geologi raised Sinabung from Level II (Waspada) to Level III (SIAGA) on 31 August following increased visual and instrumental volcanic activity. Its special report described a thick black ash column moving east and south-east and stated that the eruption was still continuing when the report was prepared.

The agency described the event as an initial eruption and said the possibility of a larger eruption could not be ruled out. At Level III, people are advised to stay out of relocated villages, within 3 km of the summit, and within a 6 km sector to the south-east.

Indonesia's disaster agency BNPB reported on 1 September that 211 families — around 615 people — from Kuta Tengah were at the emergency response shelter in Sukatepu. Residents of Payung were reported to remain at home while staying on alert.

🇺🇸 Kīlauea Episode 55 Window

Kīlauea remains paused and is not erupting, but HVO's 3 September update says summit reinflation continued over the previous day and now resembles the pattern following the last several eruptive episodes.

HVO has established a broad forecast window of 7–12 September for the possible onset of Episode 55, provided inflation continues to follow those previous patterns. Weak glow was periodically visible from the north vent overnight. Kīlauea remains at ADVISORY / YELLOW.

Episode 54 ended on 25 August after nine hours of continuous lava fountaining. HVO stresses that forecast windows can change as deformation and other monitoring data evolve.

🇵🇭 Mayon SO₂ Surge

PHIVOLCS issued a special advisory on 4 September after sulfur dioxide emissions from Mayon rose abruptly. Measurements on 3 September averaged 8,165 tonnes per day, which PHIVOLCS says is the second-highest value recorded since volcanic gas concentrations began decreasing on 16 July.

The increase was accompanied by a slight rise in low-frequency volcanic earthquakes associated with degassing and a short-term swelling or pressurisation trend on the northern and eastern sectors of the edifice. The regular 4 September bulletin recorded 10 volcanic earthquakes.

Mayon remains at Alert Level 2 — Decreased Unrest. Entry into the 6 km Permanent Danger Zone remains prohibited.

🇮🇹 Etna Brief Ash Return

Etna briefly returned to ash emission this week after INGV had declared the previous August eruptive phase over on 26 August. Toulouse VAAC advisories, using INGV webcam information and satellite imagery, reported weak ash emission on 1–2 September and an aviation colour code of ORANGE during the event.

At 09:00 UTC on 2 September, a thin ash plume was reported to approximately FL120 — around 12,000 ft / 3.7 km above sea level — moving south-east. The VAAC described the event as low intensity and did not identify a significant ash cloud.

The final Toulouse advisory at 15:01 UTC on 2 September stated that the eruption had stopped, no volcanic ash was identifiable in satellite data and no further advisories were planned.

🇯🇵 Sakurajima Eruption on 2 September

After a comparatively quiet spell late in August, Sakurajima produced another confirmed eruption this week. Tokyo VAAC reported an eruption at 05:39 UTC on 2 September, with volcanic ash reaching FL070 and extending west from the volcano.

The event was reported through JMA information supplied to the Tokyo VAAC. Sakurajima remains under Japan's established Volcanic Alert Level 3 restrictions around the crater.

🇺🇸 Alaska Three Elevated Volcanoes

AVO's 3 September update lists three elevated volcanoes in Alaska. Great Sitkin remains WATCH / ORANGE, with slow lava eruption continuing inside the summit crater and minor earthquakes detected during the previous day.

Shishaldin remains ADVISORY / YELLOW with low-level seismic unrest, while Kupreanof is also ADVISORY / YELLOW; AVO says its low-level seismic activity continues but has declined from previous levels.

🇵🇭 Kanlaon & Taal Unrest Continues

PHIVOLCS' 4 September bulletin keeps Kanlaon at Alert Level 2. Ten volcanic earthquakes were recorded during the previous 24 hours and sulfur dioxide flux measured on 3 September was 2,257 tonnes per day. Ground deformation continues to show inflation of the edifice with short-term deflation.

Taal remains at Alert Level 1. Its 4 September bulletin records one volcanic earthquake, weak plume emission and short-term inflation of Taal Volcano Island. Sulfur dioxide flux was 526 tonnes per day when measured on 1 September.

🇮🇸 Iceland No Reykjanes Eruption

There has been no new Reykjanes eruption. The latest official IMO Reykjanes assessment remains the 18 August update: slow, steady uplift and magma accumulation continue beneath Svartsengi, seismic activity is low, and the most likely eventual scenario remains another dyke intrusion that could lead to an eruption.

IMO did publish a fresh update on Múlakvísl on 1 September. The glacial outburst flood that began on 18 August was reported to be subsiding, with both conductivity and discharge decreasing and no gas pollution being detected at the time of the update.

🌍 Also on the Global Board

Official volcanic-ash advisories during the week also documented continuing ash-producing activity at several persistently active volcanoes, including Fuego, Popocatépetl, Ibu, Dukono, Semeru, Lewotolok, Sabancaya and Reventador. These are not all new eruptions: many are long-running systems where the week's advisories confirm continuing ash emissions rather than a major change in behaviour.