Taking petrologic pathways toward understanding Rabaul's restless caldera


  • Rabaul Petrology Group


Heavy falls of volcanic ash last September from active volcanos in Rabaul Harbor, Papua New Guinea, caused extensive damage to much of Rabaul, a town with a population of approximately 15,000. The ash cover is up to a meter thick in parts of the area. Roofs have fallen in, drains are blocked, power lines have collapsed, and trees are stripped of branches and leaves. Mild eruptions continue, and rehabilitation of the town is likely to take many years. Meanwhile, much of the population and the seat of the local provincial-government administration have been relocated.

In comparison to many of the area's eruptions in recent geological time, the 1994–1995 Rabaul eruptions are relatively minor, but scientific assessments are being conducted to help plan for the possibility of future major eruptions. One study has looked at the nature of the new andesitic volcanic rocks produced at Rabaul. A range of analytical techniques has been used to determine the composition of the magmas erupted during the activity, revealing subtle geochemical evidence for the incorporation of minerals that have crystallized from basalt.