The Effect of Earthquake Kinematics on Tsunami Propagation

Tsunamis are one of the most destructive effects of subduction zone earthquakes. Directly observing and understanding the generation and propagation of tsunamis remains challenging due to limited offshore instrumentation and a sparse catalog of large events. This makes linking characteristics of the earthquake rupture to their effect on tsunami generation difficult. While past studies explored how varying earthquake source geometries affect tsunami nucleation, little has been done to examine the role of the kinematic component of rupture on the tsunami; we explore these effects in this study. While past studies have examined the kinematic effect using coastal tide gauge data, we expand this examination to more recent pressure gauges. We identify a consistent rotation of the main beam of tsunami energy when using a kinematic model, affecting far-field hazards. We also identify a delay in tsunami arrival times at both coastal and open-ocean gauges that can be as long as the total source duration. For large earthquakes, this delay introduces nonnegligible mapping errors when employing open-ocean tsunami data for source characterizations. As a result of our findings we recommend including a kinematic component to tsunami modeling when studying events with source durations over 120 s and using recordings from open-ocean pressure gauges. We also find that when focusing purely on coastal gauge data and near-source hazards, the kinematic component is a much smaller contribution to the source uncertainty and can be ignored.