| 11 Dec 2025
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 MW 7.7 to 8.0 earthquakes and maximum considered MW 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.
First, I'd like to say what a pleasure it is to read a manuscript that is so well-written. So often this is not the case, and it makes it so easy to follow the technical aspects. I have only a few comments / requests regarding revision.
1) Line 33: As a seismologist, I feel compelled to mention one of my major concerns regarding the SMART sensors, that the seismic sensors should be seismometers (velocimeters), not accelerometers - or include both. Here in the introduction only acceleration is mentioned, although I see that much later in the manuscript where instruments are discussed, the authors do state that Alcatel is including both (phew!). Please be consistent. Perhaps you could say "seismic ground motions"
2) Line 55:Â a comma after "earthquakes" would improve clarity.
3) Figure 1: Great figure and combining the seismicity, bathymetry and nested computational grids is an efficient way to go - but it’s confusing to the reader to see mention of these grids and their levels without having been mentioned and defined in the text.  Normally a figure does not appear before its contents have been referenced in the body of the manuscript.  Is it possible to mention and define these grid levels before the figure appears, or, alternatively make an additional figure later in the manuscript that explicitly addresses them once they have actually been introduced to the reader? Also, grid lines are hard to see.
4) Line 81: I don't expect this to be addressed here, but I'm just curious if anyone has investigated Coulomb stress changes for the event pairs, and if the probabilities are consistent with the occurrences of secondary events.
5) Line 96: Another "just curious" - would the SMART cable deployment include sufficient slack to accommodate maximum anticipated displacements in the immediate vicinity (akin to the accommodation engineered into the Trans-Alaska Pipeline where it crosses major faults)?
6) Line 96:Â "SMART Cable would be located"
7) Lines 106-108: It seems like more references are needed here when calling out the different types of finite fault slip models, or is Yamazaki et al. intended to cover them all? I'd like to see some original works cited here.
8) Line 137: "long-periods" In the usage you have, it probably shouldn't be hyphenated (whereas short-periods is correct to be hyphenated since it serves as a single adjective) . The bigger question is that are you referring to spatial wavelength or temporal oscillations? In either case it would be nice to have a rough frequency defined, i.e., "with long periods (~20 s) consistent..."
9) Figure 2 caption:Â Slip distribution - total or vertical?
10) Line 150: modeling is made to capture the maximum scenario. For hazard planning this is prudent. Is there a most likely scenario?
Again, I really like this paper and my questions/comments amount to extremely minor changes.
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