Holocene explosive eruptions of Witori and Dakataua caldera volcanoes in west New Britain, Papua New Guinea

Witori and Dakataua caldera volcanoes have been very active in the middle to late Holocene. Using tephrochronology, this paper establishes the chronostratigraphy of these eruptions and their magnitude, and the frequency of explosive volcanism at Witori and Dakataua. After a long dormancy, Witori started explosive activity at ca. 5600 conventional radiocarbon years BP, producing in the next 4500 years five major tephra layers (W-K1 to W-K4, W-G) with VEIs of 5 to 6. After the W-G eruption at around 1200 BP, the activity decreased in magnitude but increased in frequency, with some eruptions forming central cones. The major eruption of Dakataua began with alternating ejections of phreatomagmatic ashfalls and plinian deposits followed by the cataclysmic eruption resulting in lithic-rich pyroclastic flows ca. 1100-1200 BP. The major tephra layers cover extensive areas in West New Britain due to their large volumes and the prevailing easterly winds, providing valuable time markers for establishing Holocene chronology. The largest eruption, the W-K2 event of ca. 3300 BP, shaped much of the present landscape, with an extensive area significantly devastated by tephra falls and pyroclastic flows. Obsidian and other artefacts buried by the tephras indicate that the area was repeatedly occupied. The major tephra events formed new coastal plains favourable for human occupation. Copyright (C) 1996 INQUA/Elsevier Science Ltd