Report on Ambrym (Vanuatu) — March 1986
Scientific Event Alert Network Bulletin, vol. 11, no. 3 (March 1986)
Managing Editor: Lindsay McClelland.
Ambrym (Vanuatu) Ash plume visible for 30 km
Please cite this report as:
Global Volcanism Program, 1986. Report on Ambrym (Vanuatu). In: McClelland, L (ed.), Scientific Event Alert Network Bulletin, 11:3. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198603-257040.
16.25°S, 168.12°E; summit elev. 1334 m
All times are local (unless otherwise noted)
"On 8 March an ash-laden plume issued from Ambrym and reached an altitude estimated at 3,000 m (by aircraft altimeter), remaining visible 30 km or more downwind. The volcano's last violent activity had been reported 3 months earlier."
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: R. Stoiber, Dartmouth College.