Proceedings of the 12th International INQUA meeting on paleoseismology, active tectonic and archaeoseismology

114 PATA Days 2024 The timing of the most recent event (MRE) on the fault is not well constrained. It is thought that prior to the MRE the Bumbu River occupied a course along the present-day Didiman Creek, west of the Lae CBD (Fig. 2), and that the river was diverted by the MRE. Corroboration is found in the oral traditions of villagers in Bumbu Settlement, at the mouth of the present river, who relate that the river occupied the westerly course "bepo long taim waitman ibin kam", i.e. some time before Europeans came (Liu, 1993). Lui (1993) suggests a tentative age of 250 years ago. F U T U R E W O R K Completion of OSL dating on samples taken from various terraces will allow for validation of our mapping and conceptual model. Specifically, we hope to discriminate between tectonic and non-tectonic terrace risers. An age model will then be used to constrain fault slip rates and estimate earthquake recurrence intervals. These data will form a framework for the interpretation of a paleoseismological trench that we hope to excavate across the Wongat South Thrust in coming months. Trenching will allow more accurate dating of the most recent event(s) and direct measurements of single-event displacements. Fig. 3: OSL sample site from the War Memorial Terrace (T8), showing fine sandy horizon within gravely alluvium 25 m above the low marine terrace. A C K N O W L E D G E M E N T S This project forms part of a PNGAus partnership funded by the Australian Department of Foreign Affairs and Trade. The authors wish to thank Trevor Allen and Tamarah King for their constructive reviews. The paper is published with the permission of the CEO of Geoscience Australia.