A revised age of ad 667–699 for the latest major eruption at Rabaul

The most recent major eruption at Rabaul was one of the largest known volcanic events at this complex system, having a volcanic explosivity index (VEI) rating of 6. The eruption generated widespread pumice lapilli and ash fall deposits and ignimbrites of different types. The total volume of pyroclastic material produced in the eruption exceeded 11 km 3 and led to a new phase of collapse within Rabaul Caldera. Initial 14 C dating of the event yielded an age of about 1400 years bp , and the eruption became known as the “1400 bp ” eruption. Previous analyses of the timing of the eruption have sought to link it to events in ad 536 and ad 639. However, we have re-evaluated the age of the eruption using the Bayesian wiggle-match radiocarbon dating method, and the eruption is now thought to have occurred in the interval ad 667–699. The only significant equatorial eruptions recorded in both Greenland and Antarctic ice during this interval are at ad 681 and ad 684, dates that coincide with frost rings in bristlecone pines of western USA in the same years. Definitively linking the Rabaul eruption to this narrow age range will require identification of Rabaul tephra in the ice records. However, it is proposed that a new working hypothesis for the timing of the most recent major eruption at Rabaul is that it occurred in the interval ad 681–684.