Report on Ambrym (Vanuatu) — January 1995
Bulletin of the Global Volcanism Network, vol. 20, no. 1 (January 1995)
Managing Editor: Richard Wunderman.
Ambrym (Vanuatu) Lava lakes still present in Benbow and Marum craters
Please cite this report as:
Global Volcanism Program, 1995. Report on Ambrym (Vanuatu). In: Wunderman, R (ed.), Bulletin of the Global Volcanism Network, 20:1. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199501-257040.
16.25°S, 168.12°E; summit elev. 1334 m
All times are local (unless otherwise noted)
During an aerial reconnaissance on 7 December 1994, activity was at normal levels with lava lakes present in both Benbow and Marum craters. An intermediate-depth earthquake (185 km) occurred under Ambrym on 26 April 1994. Regular monitoring is done with a seismic station on Ambrym that transmits data via ARGOS satellite to the ORSTOM office in Port Vila.
Geologic Background. Ambrym, a large basaltic volcano with a 12-km-wide caldera, is one of the most active volcanoes of the New Hebrides arc. A thick, almost exclusively pyroclastic sequence, initially dacitic, then basaltic, overlies lava flows of a pre-caldera shield volcano. The caldera was formed during a major plinian eruption with dacitic pyroclastic flows about 1900 years ago. Post-caldera eruptions, primarily from Marum and Benbow cones, have partially filled the caldera floor and produced lava flows that ponded on the caldera floor or overflowed through gaps in the caldera rim. Post-caldera eruptions have also formed a series of scoria cones and maars along a fissure system oriented ENE-WSW. Eruptions have apparently occurred almost yearly during historical time from cones within the caldera or from flank vents. However, from 1850 to 1950, reporting was mostly limited to extra-caldera eruptions that would have affected local populations.
Information Contacts: M. Monzier, ORSTOM and Vanuatu Dept of Geology, Mines and Water Resources, Vanuatu.