Tsunami hazard assessment in the southern Colombian Pacific Basin and a proposal to regenerate a previous barrier island as protection

Abstract

Abstract. In this study, the tsunami hazard posed to 120 000 inhabitants of Tumaco (Colombia) is assessed, and an evaluation and analysis of regenerating the previous El Guano Island for tsunami protection is conducted. El Guano Island was a sandy barrier island in front of the city of Tumaco until its disappearance during the tsunami of 1979; the island is believed to have played a protective role, substantially reducing the scale of the disaster. The analysis is conducted by identifying seismotectonic parameters and focal mechanisms of tsunami generation in the area, determining seven potential generation sources, applying a numerical model for tsunami generation and propagation, and evaluating the effect of tsunamis on Tumaco. The results show that in the current situation, this area is vulnerable to impact and flooding by tsunamis originating nearby. El Guano Island was found to markedly reduce flood levels and the energy flux of tsunami waves in Tumaco during the 1979 tsunami. To reduce the risk of flooding due to tsunamis, the regeneration and morphological modification of El Guano Island would help to protect Tumaco.

Coastal science for post-tsunami reconstruction

“…Post-tsunami reconstruction needs to consider the dynamics of coastal systems as part of an integrated response to tsunamis (Liew et al, 2010; Otero et al, 2014; Sonak et al, 2008). Sediments that have been eroded and redeposited inland, or moved alongshore or across-shore by tsunami waves, are subsequently reworked by coastal processes and fluvial backwash through enlarged estuaries and river channel systems (Choowong et al, 2009; Goto et al, 2011).…”