# Characterization and Modelling of Potential Seaborne Disasters, in the ANA Region
## 4 Case Study: Exxon Valdez Oil Spill Disaster (1989, Alaska)
### Discussion of Failures and Consequences  
Logic and technical details of the failure:  
The Exxon Valdez accident is an example of a number of failures of complicated man-machine systems in which attitudes, the design characteristics of the system, inadequate management, and the poor seamanship led to this disaster [30,36]. The basic cause of this incident is the human error [36]. The third mate and the captain failed to manoeuvre the ship and provide suitable navigation so as to pass through the Gulf safely [37]. Additionally, the design of the ship was poor and unsafe [30]. The regulation required the operation of double-hulled vessels in the area [32]. However, the vessel had a single hull [30]. The radar of the vessel did not work and there was absence of an effective and adequate VTS oversight in the area [32,37]. Moreover, the initial responses failed to contain the oil spill because the contingency plans in the area were inadequate for an amount of 250,000 barrels of oil [34; 36]. Also, there was clear evidence of human error since the state pilot disembarked before the ship was in open waters, which was a violation of regulations. In addition, the master was not on bridge at the time of the incident, and there was no supervision of vessel plotting.  
The consequences:  
The Exvon Valdez accident is one of the worst environmental disasters in the USA [36], the second largest oil spill in U.S. waters after the Deepwater Horizon oil spill. The collision and the grounding of the tanker in 1989 caused 250,000 barrels of oil to be poured into the Gulf [38], which was worth about $3.5 million at the time. The oil spill spread over 3000 square miles and polluted 1000 miles of shoreline [36] including beaches in Prince William Sound, one of the most pristine and magnificent natural areas in the country. The report prepared by the U.S. Environmental Protection Agency (EPA) in the wake of the disaster concluded that the very large spill size, the remote location, and the character of the oil all tested spill preparedness and response capabilities [39]. Alaska North Slope crude oil contains numerous highly toxic chemicals that can cause severe damage to flora and fauna or cause severe damage and injuries. It is estimated that throughout Alaska, the oil spill resulted in the deaths of over 250,000 seabirds, 2800 sea others, 300 harbour seals, 250 bald eagles, up to 22 killer whales, and billions of salmon and herring eggs [40]. The oil spill caused economic and psychosocial problems among local communities and native people because many of their activities, social structures, and cultural practices were established around the harvesting of maritime resources be it commercially or in terms of subsistence [29; 30]. Delayed population reductions and a cascade of indirect effects were observed, which hindered recovery [41]. This incident harmed Exvon's image extensively despite the 2 billion of dollars spent on cleaning-up efforts [42], which can be divided into marine and shore operations [43]. The coastal ecosystem is permanently damaged, and the toxic oils from discontinuous patches in the subsurface continue to impact the ecosystem near the shore and pollute the beaches. Ref. [34] estimated that Exvon spent 25 million dollars in order to repair and salvage the ship. It is also estimated that over $500 million was paid in punitive damages. Hence the consequences can be categorised into environmental, material, and community. This will be illustrated in Section 4.2.2.  
The tanks (eight of them) were ruptured, and hence these caused both damage to the vessel and oil released to the environment. Hence a good design against tanks rupturing is depicted as a safety barrier on the right side of the model. The design of the Exvon Valdez vessel was not adequate, as it was single rather than double-hull.