Design of a Sea-level Tsunami Detection Network for the Gulf of Cadiz

Abstract

Abstract. The devastating impact of the Sumatra tsunami of 26 December 2004, raised the question for scientists of how to forecast a tsunami threat. In 2005, the IOC-UNESCO XXIII assembly decided to implement a global tsunami warning system to cover the regions that were not yet protected, namely the Indian Ocean, the Caribbean and the North East Atlantic, the Mediterranean and connected seas (the NEAM region). Within NEAM, the Gulf of Cadiz is the more sensitive area, with an important record of devastating historical events. The objective of this paper is to present a preliminary design for a reliable tsunami detection network for the Gulf of Cadiz, based on a network of sealevel observatories. The tsunamigenic potential of this region has been revised in order to define the active tectonic structures. Tsunami hydrodynamic modeling and GIS technology have been used to identify the appropriate locations for the minimum number of sea-level stations. Results show that 3 tsunameters are required as the minimum number of stations necessary to assure an acceptable protection to the large coastal population in the Gulf of Cadiz. In addition, 29 tide gauge stations could be necessary to fully assess the effects of a tsunami along the affected coasts of Portugal, Spain and Morocco.

Performance of coastal sea-defense infrastructure at El Jadida (Morocco) against tsunami threat: lessons learned from the Japanese 11 March 2011 tsunami

“…From a tsunami risk point of view, the city of El Jadida was one of the Moroccan Atlantic sites ravaged by the 1 November 1755 Lisbon tsunami, as described in various tsunami historical works (Blanc, 2009;Kaabouben et al, 2009). Moreover, the study by Omira et al (2009) indicates that this site is the first on the Moroccan Atlantic coast to be reached by tsunami waves triggered by regional earthquakes generated in SW Iberia. This fact suggests that El Jadida should be an official "forecast point" in the future implementation of a tsunami early warning system in NE Atlantic.…”

“…The scaling relationship of Scholz (1982) that is based on fault lengths and length/width relation has been used to obtain the slip magnitude of each scenario. The sources HS, MP, and GB are considered thrust and thus a fixed dip of 35 • is adopted in agreement with Omira et al (2009). For the CW a minimum dip of 5 • is used as the source corresponds to the basis of an accretionary wedge (Gutscher et al, 2006).…”

“…Therefore, for an adequate simulation of near-shore tsunami propagation and overland inundation at the site of interest, we employ the nonlinear SWEs including bottom friction. We use the adapted version COMCOT-Lx (Omira et al, 2009;Omira et al, 2010;Baptista et al, 2011a) of COMCOT code (Liu et al, 1998) to solve these equations numerically. This code employs a dynamically coupled system of nested grids and solves SWEs using an explicit staggered leap-frog finite differences R. Omira: Performance of sea-defense structures in Morocco against tsunamis numerical scheme for linear terms and an upwind scheme for the nonlinear terms (Wang, 2009).…”

Tsunami Response in Semienclosed Tidal Basins Using an Aggregated Model

“…Simulation from the aggregated model shows that the fall in the level preceding the solitary wave occurs 10 min earlier than predicted by COMCOT. Omira et al (2009) concluded that the arrival time difference between linear and nonlinear computations of the same tsunami was about six minutes. Therefore, the error derived by using an aggregated model instead of an advanced model is within an acceptable order of magnitude.…”

“…Omira et al (2009) studied the tsunamigenic potential of this area, which could affect the coasts of Portugal, Spain, and Morocco. Here the COMCOT is used to model a seabed displacement of the Horseshoe/Marques de Pombal faults, so it was assumed that the epicenter was located at 36°N and 10.5°W with a 216 km long and 70 km wide surface of tectonic drift.…”