East Epi

East Epi created temporary volcanic islands in both 1920 and 1953, which were subsequently eroded back below sea level by wave action.

The summit of the most active cone (Epi B) lies just 34 m below sea level, meaning moderate eruptions can breach the ocean surface.

A 2013 research cruise recovered rhyodacitic pumice with mafic streaks from Epi B — evidence of complex magma mixing in the shallow crust.

The volcanic complex sits within a possible 10-km-diameter submarine caldera off the northeast coast of Epi Island.

Epi B was described by researchers as covered by massive blocks of pumice, indicating vigorous recent explosive activity.

The 15 recorded eruptions since 1920 have all been concentrated at or near the Epi B cone.

Discolored water — a signature of submarine volcanic gas emissions — was frequently observed from 1971 to 1974 and again in 1988.

The 1953 eruption (VEI 3) was the strongest recorded event, producing an ephemeral island and widespread floating pumice.

Approximately 5,000 people live on Epi Island, which faces directly toward the submarine volcanic complex.

The Vanuatu Volcanic Arc, which includes East Epi, is one of the most volcanically active island arcs in the Pacific Ocean.

Fishers from Epi Island are often the first to detect signs of submarine eruptions through discolored water and sulfurous odors.

The most recent eruption in January 2023 confirmed ongoing activity after a 19-year gap since the 2004 event.