DAS Recording of a Transoceanic Tsunami on Submarine Cables in Chile and its Implications for Tsunami Early Warning

The tsunami generated by the 2025 Mw 8.8 Kamchatka earthquake was recorded by a 450-km-long  distributed acoustic sensing (DAS) array leveraging telecom cables offshore Chilean coasts. Tsunami waves of ~2 cm amplitude induced measurable strain on the cable despite the low-frequency sensitivity limitations of DAS. From the conversion of the cable distributed strain-rate to water elevations considering compliance and Poisson effects, we evaluate the potential contribution to tsunami warning systems. We estimate coastal tsunami arrival times and amplitudes based on assimilation alone of the DAS data recorded at distances ranging from 10 to 30 km off the coast. We find that warning can potentially provide 3 to 15 minutes of lead time before the tsunami waves reach the coast. We also show through synthetic waveform tests that the accuracy of both arrival-time and amplitude estimates improves as longer portions of the DAS record become available. This DAS-based approach highlights the potential of leveraging existing telecommunication cables as a cost-effective and complementary tsunami warning system in many exposed regions of the world.