The 6–7 July 2010 meteotsunami along the coast of Portugal: insights from data analysis and numerical modelling

Abstract

On 6 and 7 July 2010, uncommon sea waves were observed along the coast of Portugal. The Portuguese tide gauge network recorded the sea-level signals showing tsunami-like waves of heights varying from 0.14 to 0.6 m (crest-to-trough) and of periods in the range of 30 to 60 min. Analysis of both oceanic and atmospheric data revealed the occurrence of a meteotsunami in the night of July 6th that propagated from Lagos, south, up to Viana, north. Here, we present the first investigation of the 2010 meteotsunami that struck the coast of Portugal. We use the atmospheric pressure data to force the sea surface and numerically generate the 2010 meteotsunami. We then simulate the 2010 meteotsunami propagation over high-resolution bathymetric models using a validated nonlinear shallow water code. The comparison of the simulated waveforms with the records shows satisfactory agreement of wave heights and periods in most stations. Taking the 2010 event as a reference of meteotsunamis along the Portuguese coast, we further provide an insight into the meteotsunami hazard posed by events propagating from south to north of the country. This is done by considering a 2D Gaussian-shape pressure disturbance that propagates along the shelf under varying conditions of speed and incident angle. This allows identifying “hot spots” on the coast of Portugal where the focus of meteotsunami energy is favourable. Our results suggest that meteotsunamis present a real threat on the highly occupied Portuguese coast and therefore should be considered in tsunami hazard and forecasting strategies of the NE Atlantic countries.