Ambrym Island Geology - John Seach
Ambrym Island, Vanuatu

Ambrym Island is a large basaltic shield volcano. It has a large well-preserved caldera 12 km in diameter.
Initial volcanism on Ambrym was along a north-south line forming three small volcanoes.
Post caldera formation the volcanic activity concentrated along an east-west rift zone.
Ambrym caldera was formed by quiet subsidence accompanied by eruption of lapilli.
 

Geology of Ambrym Volcano - Vanuatu
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