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

The 2018M(W)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 2018M(W)7.5 Papua New Guinea earthquake may be controlled by the immature seismogenic environment.