The Vanuatu Meteorology and Geo-hazards Department (VMGD) reported that a fissure eruption in the ESE part of the Ambrym summit caldera near the Lewlembwi crater (4 km SE of Marum) began at 0600 on 15 December, heralded by elevated seismicity detected by the seismic network and ash emissions visible in the webcam.
A notice issued later that day by VMGD stated that lava flows and lava fountains were visible, and explosions were occurring.
John Tasso, a local guide, visited the caldera a few hours after the new activity started and observed lava fountains from a fissure eruption; his video was posted to his website.
The lava fountains were about 40 m high; lava flows spread to the E part of the caldera.
Although partially obscured by a steam plume directly above the eruption site, infrared imagery from the Sentinel-2 satellite on 15 December showed lava filling much of the 500 x 900 m Lewlembwi crater and a lava flow almost as large a few hundred meters SW of that crater.
VMGD raised the Alert Level to 3 and stated that the eruption was characterized as ?small scale.? The eruption continued during 16-17 December, though reports on 17 December only described ongoing ash-and-gas emissions.
Sources: John Tasso, Vanuatu Island Experience, Port Vatu, West Ambrym, Vanuatu ,Sentinel Hub ,Vanuatu Meteorology and Geo-hazards Department (VMGD)