How Do Tides and Tsunamis Interact in a Highly Energetic Channel? The Case of Canal Chacao, Chile

Abstract

This study aims at understanding the role of tidal level, speed, and direction in tsunami propagation in highly energetic tidal channels. The main goal is to comprehend whether tide‐tsunami interactions enhance/reduce elevation, currents speeds, and arrival times, when compared to pure tsunami models and to simulations in which tides and tsunamis are linearly superimposed. We designed various numerical experiments to compute the tsunami propagation along Canal Chacao, a highly energetic channel in the Chilean Patagonia lying on a subduction margin prone to megathrust earthquakes. Three modeling approaches were implemented under the same seismic scenario: a tsunami model with a constant tide level, a series of six composite models in which independent tide and tsunami simulations are linearly superimposed, and a series of six tide‐tsunami nonlinear interaction models (full models). We found that hydrodynamic patterns differ significantly among approaches, being the composite and full models sensitive to both the tidal phase at which the tsunami is triggered and the local depth of the channel. When compared to full models, composite models adequately predicted the maximum surface elevation, but largely overestimated currents. The amplitude and arrival time of the tsunami‐leading wave computed with the full model was found to be strongly dependent on the direction of the tidal current and less responsive to the tide level and the tidal current speed. These outcomes emphasize the importance of addressing more carefully the interactions of tides and tsunamis on hazard assessment studies.

Non‐Stationary Probabilistic Tsunami Hazard Assessments Incorporating Climate‐Change‐Driven Sea Level Rise

“…The introduction of tides as a random variable may be relevant, for example, in areas where interactions between tides and tsunamis are highly nonlinear. Winckler et al (2017), for example, showed that tsunami-induced maximum elevations and current speeds are severely modified depending on the epoch of highly energetic tides (i.e., tide ranges >5 m and tidal currents >5 m/s). The tides shall be included in the scope of a future study.…”

Tsunami Resonance and Spatial Pattern of Natural Oscillation Modes With Multiple Resonators

“…A delay of 13 min at the DART Buoy 32401 is the same found by previous research due to Earth's elasticity or water density (Bai et al, ; Tsai et al, ; Watada, ). A possible explanation is that the tsunami leading wave arrived from the northeast to the Chilean coast, similar to the tidal wave, which propagates in a clockwise direction around the Pacific Ocean, therefore, the changing depth may be the major cause of tsunami‐tide interaction (Kowalik & Proshutinsky, ); thus, arrival time is reduced in larger depths (Winckler et al, ). Since most of the analysis of simulated tsunami delay has been made in deep ocean, further research on tsunami delay in coastal waters is needed.…”

Probabilistic Tsunami Hazard Assessment in South China Sea With Consideration of Uncertain Earthquake Characteristics

“…The last noteworthy source of tsunami modeling uncertainty concerns the lack of understanding of the importance of the interaction between tsunamis and other relevant coastal processes. Tides, for instance, are long waves associated with temporal changes of the sea level and currents, which could influence tsunami responses significantly under certain specific circumstances (e.g., Winckler et al, ). The aforementioned sources of uncertainty associated with bathymetry and tsunami models shall be addressed in future research.…”