Modeling tsunami and seismic waveforms from regional earthquakes to inform system design and data integration for the Tamtam SMART subsea cable

Abstract. Science Monitoring And Reliable Telecommunications (SMART) subsea cables utilize sensors integrated within repeaters to record temperature, acceleration, and pressure on the seafloor. The planned Tamtam SMART cable will connect Vanuatu and New Caledonia across a major subduction zone. Modeling recent M_W 7.7 to 8.0 earthquakes and maximum considered M_W 8.33 to 8.8 scenarios provides a range of seismic waveforms with realistic relative timing and long-period ground displacements at the sensor locations as well as coseismic seafloor uplift and subsidence at the sources used for tsunami excitation. A nonhydrostatic model describes tsunami generation, propagation, and scattering in the southwest Pacific. Spectral analysis of the computed tsunami waves shows multi-scale oscillations along the Vanuatu trench with periods from a few minutes to over an hour. The cable sensor locations are outside energetic antinodes of oscillation modes and the modeled tsunami amplitude is representative of the seismic source with minor interference from land masses. The suite of synthetic seismic and tsunami waveforms informs implementation of the sensor system for regional hazard monitoring. The Tamtam SMART cable, deployed in a very active tectonic environment with limited on-land instrumentation, will augment rapid earthquake and tsunami warning as well as source quantification.