The 2018 M_w 7.5 Papua New Guinea Earthquake: A Possible Complex Multiple Faults Failure Event With Deep‐Seated Reverse Faulting

Abstract

Although the Papuan fold and thrust belt (PFTB) is thought to accommodate convergence between the Pacific and Australian plates, the possible strain partitioning and its kinematic controls in the region are poorly understood. On 25 February 2018, a devastating Mw 7.5 earthquake jolted the southern area of the PFTB, central Papua New Guinea. The detailed imaging of the source parameters of this large earthquake is an urgent demand for a better understanding of the tectonism in the region. Here we used spaceborne interferometric synthetic aperture radar data to carefully determine the possible ruptured faults and associated fault geometries and further estimated the detailed slip of the 2018 Mw 7.5 earthquake. We find that the earthquake involved multiple faults failure, and a four‐segment fault model can reasonably produce the complex coseismic deformation, especially the observed bimodal displacements. The earthquake was dominated by reverse fault motion, and significant slip of up to ~0.7 m was documented on faults extending at depths great than 25 km. An integrated analysis of the fracture complexities suggests that possible strain partitioning in the PFTB could be tightly coupled with regional fault geometries and lithospheric properties. Our findings on the deep brittle failures suggest that crustal shortening across the PFTB could primarily control the growth of fold and thrust belt in the central Papua New Guinea.

The 2018 Mw7.5 Highlands Earthquake in Papua New Guinea: Implications for Structural Style in an Active Fold and Thrust Belt

“…One of the advantages of the InSAR technique is that it provides a widespread and mostly continuous map of ground deformation. The distribution of earthquakes relative to LOS displacement (i.e., earthquakes mostly located to the South-SW) suggests that ground deformation was related to hanging wall uplift (e.g., fault-related folding) along NE-dipping fault planes-which is consistent with moment tensor and finite-fault model solutions (USGS, 2018;Wang et al, 2020;Zhang et al, 2020). We interpret at least five distinct zones of ground deformation based on GPS measurements and the ascending and descending interferograms published on the GSI website (GSI, 2018), along with an abundance of small-scale features that may represent surface ruptures such as fissures or scarps.…”

The 2018 MW 7.5 Papua New Guinea Earthquake: A Dissipative and Cascading Rupture Process

“…Based on the InSAR data, Wang et al (2020) suggested that the 2018 M W 7.5 PNG earthquake may rupture four faults ( Figure S14) with a fault step over larger than approximately 10 km. Whether an earthquake rupture can jump a large fault step of over 10 km remains unsolved.…”

HazMapper: a global open-source natural hazard mapping application in Google Earth Engine

“…Readily observable field evidence of only the largest or most recent natural disasters typically persists in temperate environments due to the constant regrowth cycle of vegetation. Locating this field evidence and determining historical patterns of natural disasters is a primary objective for many agencies and communities (Paton and Johnston, 2001;Wegmann, 2006;Brand et al, 2019). However, fieldwork is often inefficient and expensive compared to remote sensing methods and it does a poorer job at temporally constraining natural disasters.…”