Iceland is the story this week. The Icelandic Meteorological Office published its 9 June update on the Svartsengi volcanic system and the number is remarkable: 27.5 million cubic metres of magma now stored beneath Svartsengi — up from 25 million at the end of April and 26 million in mid-May. This is the largest accumulation of magma recorded between eruptions since the Sundhnúkur crater row series began in December 2023. And the IMO's position has not changed: a magmatic dike propagation toward the Sundhnúkur crater row, which could lead to an eruption, remains the most likely scenario.
Svartsengi has been filling for nearly a year without releasing. The rate of accumulation remains slow — the slowest ever recorded in this series — but it has never stopped. At 27.5 million m³, the reservoir is now more charged than before any eruption in the 2023–2025 cycle. The IMO is explicit: the uncertainty is about timing, not about whether.
🇮🇸 Iceland — Svartsengi / Reykjanes VALS 2 · Orange
The Icelandic Meteorological Office's 9 June update confirms that model calculations based on ground deformation data now show approximately 27.5 million cubic metres of magma accumulated beneath Svartsengi since the end of the July 2025 eruption. For context: when we reported this figure in March it was 22.5 million m³, in April it was 25 million, and in May it was nearly 26 million — the accumulation is continuing steadily. The last time this was the lead story in the roundup, on 31 March, the headline figure was 24 million m³ and that itself was described as a new all-time high for the current series. The system has since added a further 3.5 million m³.
The IMO continues to report that ground uplift is ongoing, with deformation measurements showing continued inflation of the Svartsengi area. No significant changes in seismicity have been observed along the Sundhnúkur crater row or near Grindavík; most earthquakes remain below magnitude 1. The IMO hazard assessment — which identifies magmatic dike propagation toward the Sundhnúkur crater row as the most likely next scenario — is valid until 30 June 2026. The IMO has been consistent in its messaging for months: the rate of accumulation has never been slower in this cycle, while the volume stored has never been greater. That combination increases forecasting uncertainty rather than reducing it. A slow recharge is not a safe recharge. Warning times from precursory signals to eruption onset have ranged from 20 minutes to just over four hours in previous events in this series. The last eruption ended on approximately 5 August 2025 — more than 10 months ago, the longest pause in the Sundhnúkur series.
🇺🇸 Kīlauea Advisory · Yellow
Episode 49 of the Halemaʻumaʻu eruption is imminent. Summit inflation has been tracked steadily since Episode 48 ended on 1 June, with HVO's models narrowing the forecast window across the week. A slight slowing of inflation rate was noted in the 11 June HVO notice, which pushed the window from 12–15 June to 13–15 June — but the system remains on track. Both vents are glowing brightly overnight. The south vent has been particularly active during the inter-episode period, with strong glow, periodic spatter bursts, and flaming — caused by volcanic gases igniting at the vent surface. HVO have described this as the most active south vent inter-episode behaviour of the current eruption series. As of this report being published, no precursory overflow events have been recorded, which would be the first signal that Episode 49 is beginning. The pattern from Episode 48 showed that overflows can precede fountaining by 11+ hours, so south vent overflows alone do not mean fountaining is imminent.
🇵🇭 Mayon Alert 3 · 155+ days
Mayon's eruption reached its 155th consecutive day this week with no meaningful change in status. Per the GVP/Smithsonian daily activity report for 10 June (sourced from PHIVOLCS), lava effusion continues from the summit crater alongside minor episodic Strombolian activity. Plumes rose to a maximum of 1,300 m above the vent on 10 June. The seismic network recorded 312 rockfalls, 21 volcanic earthquakes, and 16 periods of volcanic tremor. Lava flow lengths remain unchanged from previous weeks: 3.8 km in the Basud Gully, 3.2 km in the Bonga Gully, and 1.8 km in the Mi-isi Gully. The Mi-isi advance that was recorded over two consecutive weeks in May appears to have stabilised. Alert Level 3 and the 6 km Permanent Danger Zone remain in force.
🇷🇪 Piton de la Fournaise Vigilance · Quiet
Piton de la Fournaise remains in its inter-eruptive quiet phase. OVPF bulletins through the week confirm that neither summit GNSS stations nor far-field GNSS stations are recording any particular signals — the brief dual-source inflation seen on 29 May was short-lived and has not recurred. Geochemically, SO₂ and H₂S at the summit remain at background levels. The notable exception continues to be CO₂ flux: both the PCRN station (Plaine des Cafres, west flank) and the GITN station (volcano lodge) have been recording elevated CO₂ ground flux since the end of the February–April 2026 eruption. OVPF's May monthly bulletin confirmed that deep magmatic system pressurisation was observed throughout May 2026. The alert level has been at Vigilance since 7 May. Four eruptions in under four months earlier in 2026, and now a two-month quiet. The question of when the system stirs again rather than if.
📡 What to watch next week
Kīlauea Episode 49 is the immediate watch — the forecast window is 13–15 June and the south vent is already spattering. Watch for overflows starting from the south vent as the precursory signal, followed by HVO's Watch/Orange notice. Given Episode 48's 11-hour overflow sequence, the window between first overflows and fountaining may be several hours. Iceland is the longer story — 27.5 million m³ is a record and the IMO's hazard assessment expires at the end of June. A new assessment will need to be issued. Monitor IMO for any sudden seismic uptick near the Sundhnúkur crater row, which in previous events has given warning times of 20 minutes to four hours.
Mayon — 155+ days, no escalation. The Mi-isi advance paused after two weeks of gains. Piton de la Fournaise — geochemically quiet but elevated CO₂ persists. If GNSS inflation returns — particularly at far-field stations — it would indicate the next eruption cycle is building.