Análise da modelagem matemática da propagação de ondas do Tsunami de 1755 na costa dos estados de Pernambuco e Paraíba Brasil, para os dias atuais

Abstract

The record of tsunamis along the Brazilian coast is less recognized in comparison with other tsunami prone regions. Historical documents report the arrival of the November 1st 1755 Lisbon transatlantic tsunami to the Brazilian coast causing anomalous shaking offshore Pernambuco and Paraíba states and costal damage. Based on this information, we propose the reconstruction of this scenario using numerical simulation of wave propagation and high-resolution digital elevation models (DEMs) at target coasts (Lucena, Pitimbu and Tamandaré) where the description of the event effects is available. The DEMs, of increasing resolution from the source area towards the coasts, were generated from a compilation of multisource elevation/depth data that include: GEBCO 30 arc-sec data, SRTM data, nautical charts available at the Centro de Hidrografia da Marinha, and LIDAR high-resolution data. Based on available seismic and tectonic information, we consider two earthquake scenarios of Mw8.6-8.8 to represent the 1755 event. To generate the initial conditions of the tsunami propagation model we compute the co-seismic deformation using the Okada s half-space elastic equations. The modeling of wave propagation is elaborated using the NSWING code (Non-linear Shallow Water Model With Nested Grids) over a system of nested grids allowing the quantification of tsunami characteristics at near-shore and coastal areas. The results of this study are presented in terms of maximum wave heights maps at regional and local scales as well as inundation maps at target coasts. Taking into account the two selected 1755-like scenarios the results present costal wave heights values ranging from 1.7 to 1.8 m at the Lucena region, ranging from 1.1 to 1.5 m at the Pitimbu region, and in the range of 1.8 to 1.9 m at the Tamandaré region. Concerning the flood values, results show inundation distances up to 3 km from the coastline, especially in locations with significant river influence, near Island of Itamaracá. We further discuss validation of these results with historical records of the period reporting the event.