Ambrym Island Eruption, October 2026
The first hints of unrest came on September 16, when the Vanuatu Meteorology and Geohazards Department (VMGD) issued a bulletin keeping Ambrym at Alert Level 2. There was nothing unusual on the surface. But the report noted that degassing and volcanic tremor were still being recorded at significant levels.
Just a day later, on September 17, villagers on the island began hearing loud rumbling and degassing sounds coming from the caldera area. By Saturday, the Volcanic Ash Advisory Centre (VAAC) in Wellington had issued a notice of an ash plume. It was estimated to be rising to 10,000 ft (3,000 m), or flight level 100, and drifting east at around 15 knots.
Photos soon emerged showing large white plumes rising from the caldera area. Then, as night fell, the glow came back. Once a common sight above the island, it lit up the sky and could be seen right across Ambrym.
Every eruption since the lava lakes drained in 2018 has been short-lived. They usually lasted only a few days and were more effusive in nature, sending lava flows across the floors of all the craters, with Benbow receiving the most lava.
This eruption has broken that pattern. At the time of writing, it has been going continuously since September 17, now three weeks and counting.
High-level heat signature, 20/9/26, MODIS
From the start, the satellites have shown intense heat in Marum, ground uplift around the summit, and plenty of gas.
Thermal anomalies pointed to Marum crater from the outset. They have stayed very high, reaching upwards of 2,000 MW (MODIS).
Radar interferometry shows the ground rising. The interferogram below compares September 13 with September 25. The fringes around the summit craters show uplift over that period, which suggests magma was pressurising the system beneath the summit.
Each full cycle of colour represents 2.8 cm of ground movement along the satellite’s line of sight. Mounts-Proejct.
The volcano is also still producing elevated sulphur dioxide (SO2) emissions, according to Sentinel-5P data.
What started as more explosive activity producing ash plumes has since changed character (at least for now). It appears to have moved into a mix of Strombolian activity and periods of fire fountaining, throwing out lava projectiles – and now, a swirling lake of molten lava.
So what’s going on?
Well we got our first information from villagers who described a new vent area, not where the old lava lake used to be, and said it was building up a cone. And then today we finally received a clear satellite image, and it shows two active vents… and there is a strong possibility that both have morphed into lava lakes. All activity is confined to Marum’s Mbwelesu crater.
Sentinel-2 True Colour
The western vent is the larger of the two. At around 80 m across, it is bigger than Marum’s former main persistent lava lake was before it drained and collapsed. Neither site is necessarily new. Both have hosted small, semi-persistent lava lakes at times over the last 20 years or so. Both also sit away from the old main lake, which likely explains why the activity looked like a new vent from the ground. The location of the old main Marum lava lake is not active.
Sentinel-2 False Colour-Urban, showing lava flows and the crater floor covered in fresh lava.
There is no lava or activity in the other craters either: Benbow, Niri Taten and Niri Mbwelesu are all quiet. The inner crater wall shows staining typical of tephra, lapilli and ash deposits. The colour of these deposits may point to fire fountaining.
We can’t yet categorically confirm that these are lava lakes. That will take direct observation. But the signs are encouraging. Three weeks of sustained activity, very high thermal output, continuing gas emissions and two active vents on the crater floor. For a volcano whose post-2018 eruptions have been over within days, that alone is a change.
Which leaves the big question. Will these lakes stay around and become persistent, the way Ambrym’s lava lakes once were?
As always, please seek official information and updates from VMGD.