Late quaternary uplift in eastern Indonesia

Radiocarbon dates of fifteen samples representing raised shorelines on various islands of the tectonically mobile region of eastern Indonesia suggest rates of tectonic uplift ranging up to 12.5 mm/year. Low rates of 0.35–1.2 mm/year are from Biak Island and are averages for the last 31,000–36,000 years. The low rates may be explained to indicate subsidence alternating with uplift, both of which occurring under influence of the large Irian fault zone that passes to the immediate south of the island. Very young elevated strandlines (250 years BP) indicate rates of uplift between 8 and 12.5 mm/year which seem to demonstrate the episodic character of vertical diastrophic movements. Intermediate rates of uplift are in the order of 5 mm/year and may represent averages for eastern Indonesia.