Tsunami vulnerability assessment of Casablanca-Morocco using numerical modelling and GIS tools

Abstract

Earthquakes and tsunamis along Morocco's coasts have been reported since historical times. The threat posed by tsunamis must be included in coastal risk studies. This study focuses on the tsunami impact and vulnerability assessment of the Casablanca harbour and surrounding area using a combination of tsunami inundation numerical modelling, field survey data and geographic information system. The tsunami scenario used here is compatible with the 1755 Lisbon event that we considered to be the worst case tsunami scenario. Hydrodynamic modelling was performed with an adapted version of the Cornell Multigrid Coupled Tsunami Model from Cornell University. The simulation covers the eastern domain of the Azores-Gibraltar fracture zone corresponding to the largest tsunamigenic area in the North Atlantic. The proposed vulnerability model attempts to provide an insight into the tsunami vulnerability of building stock. Results in the form of a vulnerability map will be useful for decision makers and local authorities in preventing the community resiliency for tsunami hazards. Addresses: [Omira, R.; Baptista, M. A.; Miranda, J. M.] Univ Lisbon, Fac Ciencias Lisboa,

Tsunami hazard assessment in the coastal area of Rabat and Salé, Morocco

“…As reported by Miranda et al (1996), Omira et al (2010) and Guesmia et al (1998), we also observe a gap on the arrival time of tsunami wave of about 15 min (Fig. 13), probably due to a lack of data calibration for the Casablanca tide gauge as pointed out by Omira et al (2010): "In the case of the February 1969 event, the unique record available to us is a hand copy drawing of the filtered signal showing a first arrival of 0.9 m downward". In our simulations, the highest amplitude is observed for the first wave, whereas it corresponds to the forth one in the observations.…”

“…First, it is possible that we did not simulate the worst case of the 1755 earthquake. Indeed, after validation of the scenario sources by the SCHEMA project, Omira et al (2010) proposed 4 different earthquake models that had probably generated the earthquake of 1 November 1755. The authors considered that the model 4 (N 160 source) corresponds to the worst case earthquake scenario, and assumed that all these earthquake models infer a magnitude of 8.3-8.5., and represent the WYCC (Worst Yet Credible Case) of a tsunami impacting Casablanca, located at 80 km south of Rabat.…”

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

“…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).…”

“…In the Gulf of Cadiz coastal areas, various studies have been addressed to investigate tsunami impact (Lima et al, 2010;Omira et al, 2011;Baptista et al, 2011a), and the area's vulnerability . These works and this paper show the high level of destruction that coastal areas of Morocco, Portugal and Spain could experience following the occurrence of large regional tsunami events, and hence the need for robust TWS in the region to mitigate the tsunami hazard.…”

Simulation of tsunami generation, propagation and coastal inundation in the Eastern Mediterranean

“…The sequence of a tsunami hitting the coast comprises a series of processes: from the tsunami generation and propagation, to coastal-zone hydrodynamics (including surf and swash zone dynamics), coastal inundation and wave-structure interactions with the built environment. Regarding the modeling part -and focusing on coastal inundation -exemplary reference can be made to the work of Borrero et al (2006), who used the MOST model (Titov and González, 1997) for tsunami generation and inundation in western Sumatra; Gayer et al (2010), who used the MIKE21 Flow Model FM to simulate inundation based on roughness maps for Indonesia; Omira et al (2010), who applied a modified version of the COMCOT model (Liu et al, 1998) to selected cases in Casablanca, Morocco; Apotsos et al (2011), who used the Delft3D model to study inundation and sediment transport by the 2004 SE Asia tsunami in measured and idealized morphologies; and Løvholt et al (2012), who used models based on the Boussinesq equations for tsunami propagation and nonlinear shallow-water wave equations for coastal inundation to simulate the 2011 Tohoku tsunami. Extending to coastal planning, vulnerability assessment and tsunami hazard mitigation, one may refer to the work of Bernard (2005), González et al (2009), Post et al (2009, Kumar et al (2010), Sørensen et al (2012) and González-Riancho et al (2014).…”