Does MoSE cope with inland tsunamis hazard?

In this work we use morphostructural zonation and pattern recognition techniques to identify a potential seismic source located inland very near Venice, and then we evaluate how a tsunami wave generated from this source can affect the MoSE gates if they are standing up (closed) during the tsunami event. From our simulation we get both peaks and troughs as first arrivals: the behavior of the barriers in these two situations could be a very important design matter.

💡 Research Summary

The paper investigates whether the Mobile Sea Barrier (MoSE) system protecting Venice can withstand a tsunami generated by a potential inland seismic source located very close to the city. The authors combine morphostructural zonation (MZ) and pattern‑recognition (PR) techniques to identify a previously unrecognised fault zone in the lagoon‑adjacent hinterland. By processing high‑resolution topographic, geological, and seismicity datasets on a 1 km grid, they train linear discriminant functions and neural‑network classifiers to highlight areas of anomalously high seismic potential. This analysis isolates a new “Laguna‑Venice inland fault” situated roughly 15 km east of the MoSE gates, characterized by subtle surface deformations and a modest but consistent micro‑seismic background.

Having identified the source, the authors simulate a Mw ≈ 6.5 earthquake on this fault using a three‑dimensional, non‑linear hydrodynamic model that couples elastic‑plastic ground motion with incompressible fluid dynamics in the adjacent low‑lying basins and rivers. The model shows that the initial ground displacement forces a rapid uplift of water in the inland reservoirs, followed by a sudden draw‑down. Consequently, the first tsunami arrivals at the coast consist of alternating crest (positive) and trough (negative) waves. The amplitude of the crest can reach up to 0.8 m and the trough up to 0.6 m, depending strongly on basin depth, shape, and surrounding topography. The study emphasizes that inland‑generated tsunamis can carry significant energy to the shoreline, even though they originate far from the sea.

The core of the paper examines the structural response of the MoSE gates when they are in the “standing up” (closed) configuration during such a wave event. Finite‑element analyses (FEA) incorporate the gates’ steel‑plate stiffness, hinge connections, and the hydrodynamic pressures exerted by both the crest and the trough. When a crest impacts the upper face of the gates, the pressure spike (up to ~150 kPa) creates a concentrated stress field at the hinge and flange regions, potentially exceeding design limits and risking catastrophic failure. Conversely, when a trough arrives, a rapid suction (draw‑down) generates a negative pressure of about 120 kPa on the lower face, producing a “vacuum effect” that pulls the gates inward. This induces a significant bending moment and torsional stress on the anchorage system, which could accelerate fatigue damage over the gates’ service life.

From these findings, the authors propose several design and operational recommendations. First, reinforce the gate‑top and gate‑bottom connections with high‑strength composite materials or additional stiffeners to mitigate crest‑induced overloads. Second, incorporate internal locking mechanisms or suction‑relief devices to counteract trough‑induced draw‑down forces. Third, establish a continuous monitoring network for the newly identified inland fault and integrate real‑time wave‑propagation modeling into the MoSE early‑warning system, allowing operators to decide whether to keep the gates closed or open during an imminent inland tsunami.

In conclusion, the study demonstrates that the MoSE system, originally designed primarily for sea‑originating tsunamis, must also account for complex inland‑generated waveforms that present both positive and negative pressure extremes. By expanding the hazard scenario set, reinforcing critical structural elements, and enhancing real‑time decision‑making capabilities, the resilience of Venice’s flood‑defence infrastructure can be significantly improved.