IMAGES AND PHOTOS IN ERUPTION ON THE ACTIVES VOLCANOES OF THE WORLD

Ambrym island in the archipelago of VANUATU
(666 km2 ; 44 x 30 km between 16°15’S et 168°05’E)


Ambrym is a large basaltic volcano with a 12-km-wide caldera, is one of the most active volcanoes of the New Hebrides arc. It is located on the homonymous island Ambrym. 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 (C-14 dating).
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.

© Yashmin CHEBLI
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