Bruce Thomas, Tasnîme Louartani

Ability of a cargo-ship GNSS network to detect tsunamis

Many of the most devastating natural hazards that impact our communities are generated over, or under, the oceans. The recent Tonga volcano eruption caused an unexpected tsunami that was poorly monitored, demonstrating the urgent need for more densely spaced observations and direct measurements from the areas between the source region and the communities that may be impacted – that is, across the oceans. Most of the existing observing capacity is located on land, close to the shore, or only sparse (seismic network, land-based GNSS, tide-gauges and DART array), limiting our ability to predict, detect and respond to these hazards. To fill the geodetic desert in the oceans and improve hazard mitigations, we propose the development of a network of ships with geodetic GNSS systems tracking changes in sea-surface height, that are able to detect even small amplitude tsunamis (10 cm).

Using one year of navigation data from the commercial shipping fleet, we generated several statistical coverage maps of large ships for different epoch in the Pacific region. By overlapping these maps with tsunami source regions, we demonstrate that commercial shipping lines provide excellent temporal and spatial coverage of the ocean globally and, critically for local and regional early warning, are at their most dense near coastlines. More results, based on running tsunami models and analyzing predicted amplitudes, describe some first insights into how this proposed cargo-ship network might experience tsunamis, exploring the geographic relationship between tsunami sources, ships locations, and the ship network’s detection of the hazard.

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