Abstract: The recent Mw=7.8 Kaikoura (New Zealand) earthquake involved a remarkably complex rupture propagating in an intricate network of faults at the transition between the Alpine fault in the South Island and the Kermadec-Tonga subduction zone. We investigate the main features of this complicated rupture process using long-period seismological observations. Apparent Rayleigh-wave moment-rate functions reveal a clear northeastward directivity with an unusually weak rupture initiation during 60s followed by a major 20s burst of moment rate. To further explore the rupture process, we perform a Bayesian exploration of multiple point-source parameters in a 3-D Earth model. The results show that the rupture initiated as a small strike-slip rupture and propagated to the northeast, triggering large slip on both strike-slip and thrust faults. The Kaikoura earthquake is thus a rare instance in which slip on intraplate faults trigger extensive interplate thrust faulting. This clearly outlines the importance of accounting for secondary faults when assessing seismic and tsunami hazard in subduction zones.

Abstract: The action of predators, such as diurnal raptors, owls, mammals or humans, influence the nature of small vertebrate fossil assemblages but currently their taphonomic features are still poorly understood. In this study, we investigate the taphonomic signature of the snowy owl (Bubo scandiacus) based on an analysis of pellets collected at breeding sites located in Greenland and the Canadian Arctic. This taxon is widely distributed through the North Hemisphere and was an important predator in Pleistocene times. Taphonomic parameters suggest that, contrary to previous assumptions, B. scandiacus produces, on average, moderate digestion of incisors, molars and post-cranial elements, and should be classed as a Category 3 or Category 3/4 predator according to the terminology established by Andrews. Significant inter-site variability was observed for some of the damage considered (in particular, digestion on incisors), and a key finding is that variability and the associated statistical confidence intervals are crucial notions that should be taken into account when assessing taphonomical features, in order to reliably identify the potential predator(s) responsible for small vertebrate fossil accumulations.

Abstract: In highly social top predators, group living is an ecological strategy that enhances individual fitness, primarily through increased foraging success. Additive mortality events across multiple social groups in populations may affect the social structure, and therefore the fitness, of surviving individuals. This hypothesis was examined in a killer whale (Orcinus orca) population that experienced a 7-y period of severe additive mortality due to lethal interactions with illegal fishing vessels. Using both social and demographic analyses conducted on a unique long-term dataset encompassing periods before, during, and after this event, results indicated a decrease in both the number and the mean strength of associations of surviving individuals during the additive mortality period. A positive significant correlation between association strength and apparent survival suggested that the fitness of surviving individuals was impacted by the additive mortality event. After this event, individuals responded to the loss of relatives in their social groups by associating with a greater number of other social groups, likely to maintain a functional group size that maximized their foraging success. However, these associations were loose; individuals did not reassociate in highly stable social groups, and their survival remained low years after the mortality event. These findings demonstrate how the disruption of social structure in killer whales may lead to prolonged negative effects of demographic stress beyond an additive mortality event. More importantly, this study shows that sociality has a key role in the resilience of populations to human-induced mortality; this has major implications for the conservation of highly social and long-lived species.