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

Abstract

The 2018 MW 7.5 Papua New Guinea earthquake is the largest earthquake instrumentally recorded in the Papuan Fold Belt since 1900. Based on a combined analysis of backprojection imaging and finite‐fault joint inversion, we determined a complex spatiotemporal rupture model of the mainshock. During the rupture process, three major asperities were ruptured successively with relatively low rupture velocities ranging from 1.9 to 2.3 km/s. The spatiotemporal evolution of the imparted Coulomb stress indicates that the rupture of the preceding asperity played an important role in triggering the delayed rupture of the adjacent asperity. Based on our rupture model, the upper bound of the radiation efficiency of this event is estimated to be 9.7–12.3%, a relatively low value, indicating that this earthquake is extremely dissipative. The high energy dissipation implies that the 2018 MW 7.5 Papua New Guinea earthquake may be controlled by the immature seismogenic environment.

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.…”

“…Cross-sections are constrained by surface (i.e., field geological) and subsurface (i.e., well, seismic reflection) data and have been calibrated with the Bouguer gravity data set shown in Figure 7 aperture radar (SAR) data have yielded highly variable predictions of the number and orientation of faults activated during the event. After testing both single-and multiple-fault models, Wang et al (2020) conclude that a four-fault model best fits the data, whereas Zhang et al (2020) argue for a single-fault model. Chong and Huang (2020) present a model containing three faults (including a detachment).…”

Supershear Rupture During the 2021 MW 7.4 Maduo, China, Earthquake

“…The main rupture characteristics revealed from the single array back‐projection results are similar to our preferred multi‐array back‐projection results; however, some significant discrepancies can be spotted visually (Figures 2a–2c and 2e). These discrepancies are likely caused by the limited azimuth coverage of an individual array which can artificially enhance rupture energy toward the array (Kiser & Ishii, 2012; Wang & Mori, 2016; Zhang et al., 2020). As proposed by some previous studies, the combination of multiple arrays can significantly increase azimuth and distance coverage, and hence mitigates the above potential artifacts from an individual array and better constrains the HF sources radiated from a large earthquake with a complex rupture process (e.g., Kiser & Ishii, 2012; Xie & Meng, 2020; Zhang et al., 2016).…”

Rupture Process of the 2020 Mw7.0 Samos Earthquake and its Effect on Surrounding Active Faults

“…These zones of stress increases and decreases, respectively, have been associated with areas where faults are either loaded or relaxed and accordingly have significant implications for seismic hazard. In this context, changes in the Coulomb failure stress as small as 0.1 bar have been used to assess seismicity rate changes and aftershock distributions, infer earthquake interactions, and draw conclusions on advances or delays in the occurrence of future events (e.g., Harris & Simpson, 1992; Steacy et al., 2005; Xiong et al., 2017; Zhang et al., 2020).…”