This Week
in Fire

Mayon is the story this week — and it has changed significantly. Sulphur dioxide emissions that had been running at roughly 1,000–2,600 tonnes per day since May have now spiked to 7,475 t/day on 10 July and 9,028 t/day on 15 July. Pyroclastic density current activity has also increased, with 10 PDC signals recorded in a single day on 15 July. The Mi-isi flow has advanced to 2.1 km. Nearly 300,000 people are classified as affected across Region V. This is a meaningful escalation in a 190-day eruption.

🇵🇭 Mayon Alert 3 · Escalating

Mayon's eruption entered its 190th consecutive day this week with a clear intensification in monitoring data. The GVP/Smithsonian daily activity report for 10 July (sourced from PHIVOLCS) shows the first significant change in Mayon's flow lengths in weeks: the Mi-isi Gully flow has advanced to 2.1 km, up from the 1.8 km it had been at since May. The Basud Gully flow remains at 3.8 km and the Bonga Gully flow at 3.2 km. More significantly, SO₂ emissions on 10 July averaged 7,475 tonnes per day — a sharp increase from the 988–2,615 t/day range that had persisted since late May.

By 15 July, the escalation had deepened further. PHIVOLCS reported 187 volcanic earthquakes on 15 July — including 43 volcanic tremors lasting between 5 and 45 minutes each — 398 rockfall events, and 10 pyroclastic density current signals. Sulphur dioxide emissions on 15 July averaged 9,028 tonnes per day — the highest SO₂ output recorded in the entire 2026 eruption and nearly five times the levels seen as recently as June. This level of SO₂ emission is associated with vigorous degassing of fresh magma and indicates increased lava effusion rates. Alert Level 3 is maintained with the 6 km Permanent Danger Zone in force.

The human impact has grown substantially. The Philippine Department of Social Welfare and Development reported that as of 18:00 local time on 13 July, 71,552 families — 293,974 persons — were classified as affected across 159 barangays in Region V. A total of 1,128 families (4,113 persons) were displaced, with 1,088 families staying in 12 evacuation centres and 40 families with relatives or friends. PHIVOLCS has not raised the Alert Level above 3, but the combination of elevated SO₂, increased seismicity, more frequent PDCs, and advancing lava flows represents the most active phase of the 2026 Mayon eruption to date.

🇺🇸 Kīlauea Advisory · Yellow

Episode 51 of the Halemaʻumaʻu eruption began at approximately 8:30 AM HST on 15 July — the same day Mayon's escalation was being reported — and ended abruptly at 4:46 PM HST on 15 July, after 8.3 hours of continuous lava fountaining from the north vent. The south vent did not fountain during Episode 51, though it emitted flames and gas jets throughout. Peak fountain height was approximately 950 feet (290 metres) above ground level, reached at around 10:30 AM HST. The peak instantaneous effusion rate at that time was approximately 370 cubic yards per second (280 m³/s), with an average effusion rate of 200 cubic yards per second (150 m³/s) across the entire episode. An estimated 6.6 million cubic yards (5.1 million cubic metres) of lava was erupted, covering approximately 50% of the Halemaʻumaʻu crater floor. The volcanic plume reached 18,000 feet above sea level. Tephra remained within the closed area of Hawaiʻi Volcanoes National Park — no populated areas reported tephra impact.

Summit reinflation began immediately after Episode 51 ended and both vents are producing bright glow overnight, with numerous incandescent spots visible from the fresh lava field. HVO has confirmed another fountaining episode is expected but has stated that more inflationary tilt data is needed before a forecast window for Episode 52 can be determined. The V1 camera remains on its temporary assignment monitoring the localised subsidence area on the western floor of Halemaʻumaʻu, which has persisted across several recent episodes.

🇷🇪 Piton de la Fournaise Vigilance · Building

Piton de la Fournaise has now been in a sustained pre-eruptive inflation phase for approximately six weeks — since at least 15 June — without an eruption beginning. This is the longest continuous pre-eruptive build-up of the entire 2026 eruption cycle. OVPF daily bulletins confirm that both the summit GNSS stations and far-field GNSS stations continue to record inflation, indicating simultaneous pressurisation of both shallow and deep magmatic sources. Elevated CO₂ flux at the PCRN and GITN monitoring stations has also been maintained throughout. The alert level remains at Vigilance. The extended duration of this build-up — significantly longer than those that preceded the four earlier 2026 eruptions — may indicate that a greater volume of magma is accumulating before the next eruptive phase begins. OVPF are monitoring 24 hours a day.