Space geodetic evidence of basement-involved thick-skinned orogeny and fault frictional heterogeneity of the Papuan Fold Belt, Papua New Guinea

Abstract

Knowledge of the fault kinematics underlying the Papuan Fold Belt is important for better understanding the evolution of the orogen, but the active and long-term tectonics of the region remain widely debated. The 2018 Mw 7.5 Papua New Guinea earthquake provides an unprecedented opportunity to probe the active fault structure deep in the Papuan Fold Belt. Here, we use Interferometric Synthetic Aperture Radar data from four ALOS-2 acquisitions to study coseismic and postseismic ground deformation and invert for fault slip models. The results show that the oblique reverse earthquake reactivated a flat-ramp structure and ruptured through most of the crust with the majority of coseismic slip confined between 5 and 25 km. Additionally, we found three separated postseismic slip zones with variable spatial complementarity between coseismic and postseismic slip, dip-slip/strike-slip ratio, and seismic/aseismic budget at three separated postseismic slip zones. Our results demonstrate that thick-skinned tectonics dominate the current state of Papua New Guinea frontal orogen evolution.