Multiple observations of the July 2024 Sicily Channel meteotsunami from coastal seismology, pressure-sea level networks and High Frequency radar sensors

Meteotsunamis are sea-level oscillations within the conventional tsunami period band (minutes to hours) generated by fast-moving atmospheric disturbances rather than by seismic, volcanic or mass-movement sources. They belong to the broader family of non-seismic sea-level oscillations at tsunami timescales (NSLOTT), which can contribute substantially to coastal extremes and therefore deserve explicit consideration in hazard assessments. In the Mediterranean, meteotsunamis are commonly reconstructed from atmospheric pressure and tide-gauge data, while constraints on nearshore impact and the associated circulation response remain comparatively limited. Although several Mediterranean events have been investigated, detailed reconstructions for the Strait of Sicily and the adjacent Maltese shelf are still limited.

In this work, supported by the Interreg VI-A Italia–Malta project WAVEGUARD, we examine the July 2024 Sicily Channel meteotsunami (“Marrobbio”) using a tightly co-located, multi-sensor dataset that combines barometric arrays and tide gauges with two observational components that are still underexploited for this class of events: coastal seismometers and high-frequency (HF) coastal radars, complemented by atmospheric reanalysis. Coastal seismic stations provide a direct, time-resolved proxy for shoreline impacts. Time–frequency analysis of the seismic wavefield isolates long-period energy and resolves distinct impact phases, yielding robust arrival windows even where sea-level records are unavailable or strongly affected by local filtering. Tide-gauge residuals from resonance-prone harbors show sustained oscillations consistent with strong port amplification and a dominant shelf/harbor control on the recorded signal.

Using the pressure networks, we triangulate the translating atmospheric disturbance and retrieve a fast NW–SE moving front (~18–24 m s⁻¹). This speed is consistent with the expected long-wave phase speed over the broad, shallow Sicilian shelf, supporting near-Proudman conditions as the main pathway for efficient energy transfer. We then apply the same timing framework to tide-gauge residual onsets and to seismic vector-RMS arrivals. Both reproduce the NW–SE progression but yield much lower apparent speeds (~2–6 m s⁻¹), demonstrating that the propagation inferred from sea level and seismicity primarily reflects delayed oceanic adjustment and resonance effects, rather than the atmospheric forcing kinematics.

HF radar measurements independently capture short-lived anomalies in nearshore surface currents that coincide with the strongest sea-level oscillations, indicating that this meteotsunami measurably modulated coastal circulation. Overall, the combined observations constrain the full atmosphere–ocean–solid earth response chain for the July 2024 event and demonstrate how integrating coastal seismology and HF radar with routine pressure and sea-level monitoring can improve detection and characterization of meteotsunamis in the central Mediterranean, with clear implications for future operational warning.