Report on Epi (Vanuatu) — 25 January-31 January 2023
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
25 January-31 January 2023
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2023. Report on Epi (Vanuatu). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 25 January-31 January 2023. Smithsonian Institution and US Geological Survey.
16.68°S, 168.37°E; summit elev. 833 m
All times are local (unless otherwise noted)
The Wellington VAAC reported that a low-level plume of ash and sulfur dioxide from a new eruption at Epi was identified in satellite data at 0730 on 31 January. According to the Vanuatu Meteorology and Geo-Hazards Department (VMGD) residents saw steaming at the ocean’s surface in the area over the vents at around 0748, and phreatic explosions that ejected steam and tephra 100 m above the water. The Alert Level was raised to 1 (on a scale of 0-5) and the public was warned to stay 10 km away from the East Epi submarine volcano. Observers reportedly saw a growing cone from ongoing ash emissions. The VAAC noted that the eruption was short-lived and had ceased by 1548; the ash had dissipated.
Three submarine cones, Epi A, Epi B, and Epi C, and smaller cones and craters, are located 10-16 km NNE from the summit of Epi Island and are aligned along the N rim of an inferred caldera. Epi B is the shallowest of the seamounts and has been historically active, most recently in February 2004. A March 2004 bathymetric survey revealed that Epi B was about 300 m tall, with a diameter of about 1.8 km at the base. The summit crater was about 150 m in diameter and the crater floor was at a depth of 90 m. The highest point was on the NW rim of the summit crater, at a depth of 34 m.
Geological Summary. A large caldera, with submarine post-caldera cones active in historical time, lies off the eastern coast of Epi Island. Epi Island itself, located slightly west of the main New Hebrides volcanic arc, largely consists of two Quaternary volcanoes, Mount Allombei on the west and Pomare (Tavani Kutali) on the east. Tavani Ruro, which forms an elongated eastern extension of Epi Island across a narrow isthmus, is related to Kuwae caldera to the east. Pomare volcano is the highest point on the island and has three well-preserved subsidiary cones to the east with youthful summit craters. Pomare volcano is truncated on its eastern side by the largely submarine East Epi caldera, which has been the source of all historical eruptions. Three small submarine basaltic and dacitic cones, known as Epi A, Epi B, and Epi C, are located along the northern rim of the breached caldera. Ephemeral islands were formed during eruptions in 1920 and 1953, and the summit of the shallowest cone, Epi B, was at 34 m below sea level at the time of a 2001 survey.
Sources: Vanuatu Meteorology and Geo-Hazards Department (VMGD), Wellington Volcanic Ash Advisory Center (VAAC)