Abstract
The southwest Pacific is one of the most tsunami-prone regions worldwide, owing to its complex tectonic setting dominated by active subduction zones and frequent tsunamigenic earthquakes. Approximately one quarter of all recorded tsunamis originate from this region, including several events that have severely affected vulnerable coastal communities in the Solomon Islands. However, these events have been recorded by only a limited number of coastal gauges and DART stations, reflecting the sparse coverage of existing tsunami observation systems and the challenges associated with timely offshore detection. Here, we investigate the potential of augmenting existing monitoring systems with cargo ships equipped with geodetic-grade GNSS instruments capable of detecting sea-surface perturbations. Specifically, we (i) model the 2016 Solomon Islands tsunami using available observations, (ii) evaluate tsunami travel times and expected wave amplitudes observable by moving GNSS-equipped cargo ships, and (iii) assess their contribution to tsunami detection across a range of plausible scenarios. Our results suggest that first, ship motion, trajectory direction, and water depth do not prevent tsunami detection, and second, for tsunami magnitudes exceeding M W 7.0, a cargo-ship-based GNSS network could enhance the current monitoring capabilities in the Solomon Islands and more broadly in the southwest Pacific, providing a low-cost, complementary observing system that helps fill offshore observational gaps.