Kermadec 2021 refined earthquake catalogue and slip models

Earthquake catalogue and slip models for 2021 Kermadec earthquake sequence. From Lythgoe et al, Earth and Planetary Science Letters (Accepted). The ruptures of the 2021 Mw7.4 and Mw8.1 doublet earthquake sequence in the Kermadec subduction zone are investigated and compared to the 1976 doublet that occurred at the same location. We find that although the 2021 mainshock likely re-ruptured the same asperity as the 1976 Mw7.9 event, the detailed slip distribution is different. Other ruptures in the doublets also differ in character and location. Our observations indicate the variability between large earthquakes on the same segment of the plate boundary in each earthquake cycle. This high-seismicity segment is coincident with an isolated forearc sedimentary basin, possibly formed by basal erosion related to seismogenesis, suggesting that seismic slip has persisted here for several million years. Refined up-dip aftershock and background seismicity focal mechanisms have a steeper dip angle than the slab interface, suggesting these events are located within the subducting oceanic slab, possibly forming a rougher plate interface that facilitates basal erosion. We conclude that the stress heterogeneity within this bounded seismogenic zone is long-lived and has produced a rich spectrum of earthquake ruptures.