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

110 PATA Days 2024 1 2 T H I N T E R N AT I O N A L I N Q U A M E E T I N G O N PA L E O S E I S M O L O G Y , A C T I V E T E C T O N I C S A N D A R C H A E O S E I S M O L O G Y ( PATA ) , O C T O B E R 6 T H - 1 1 T H , 2 0 2 4 , L O S A N D E S , C H I L E K E Y W O R D S Papua New Guinea, seismic hazard, tectonic geomorphology (1) Community Safety Branch, Geoscience Australia. (2) Earth Sciences Division, School of Natural & Physical Sciences, University of Papua New Guinea *Email: dan.clark@ga.gov.au Dan Clark (1) Jonathan Griffin (1) Joseph O. Espi (2) Leo Jonda (2) Phil Cummins (1) Hadi Ghasemi (1) TECTONIC GEOMORPHOLOGY AND HOLOCENE UPLIFT RATES OF THE LAE URBAN AREA, PAPUA NEW GUINEA A B S T R A C T The city of Lae is Papua New Guinea’s (PNG’s) second largest and is the home of PNG’s largest port. Here, a convergence rate of ~50 mm/yr between the South Bismarck Plate and the Australian Plate is accommodated across the Ramu-Markham Fault Zone (RMFZ). The active structures of the RMFZ bifurcate immediately west of the Lae urban area, with one strand (the Wongat South Thrust) trending southeast through Lae City and connecting to the Markham Trench within the Huon Gulf. The geomorphology of the Lae urban area relates to the interaction between riverine (and limited marine) deposition and erosion, and range-building over the Wongat South Thrust. Flights of deformed river terraces imply repeated tectonic uplift events. Terrace riser heights are typically on the order of 3 m, indicating causative earthquake events of greater than magnitude 7. The results of a tectonic geomorphology study will inform a seismic hazard and risk assessment. I N T R O D U C T I O N The Australian Department of Foreign Affairs and Trade is supporting Geoscience Australia, the University of Papua New Guinea, the PNG University of Technology and Morobe Provincial Disaster Office to undertake an earthquake risk assessment for Lae City and surrounding region. Herein we report upon the earthquake geology component of the assessment. Lae is PNGs second largest city (population ~200,000 people, https:// lca.gov.pg/about-lca/), its largest industrial hub, and home of the country’s largest port. It also has some of the highest seismic hazard in the country (Ghasemi et al., 2020).