ABSTRACT

Oil storage tanks in industrial zones along the coastal lines have a high risk of oil spill in case of tsunami attack. The occurrence of major oil spill depends on the possibility of oil storage tank drifting with the tsunami run up. The occurrence of the oil spills from these tanks is estimated in Japan by safety factors based on theoretical assumption according to the guidelines of Fire and Disaster management Agency (FDMA) of Japan. This study conducted experiments and numerical simulations to revise the guidelines of FDMA and propose its modification.

INTRODUCTION

In 2011 Great East Japan Earthquake unleashed a major tsunami which devastated ports and industrial complexes, which comprises oil storage tanks and other hazardous material facilities, in the northeast of Japan main land. Since the 2004 Indian Ocean tsunami caused by the Sumatra earthquake, it was aware of tank drifting and damage by tsunami inundation (Saatcioglu et al., 2006). Although there was no tsunami- triggered oil spill case reported after the Indian Ocean tsunami, there was major oil spills from the damaged oil storage tanks in the case of Japan.

In Kesennuma City, 22 out of 23 oil storage tanks, located at the entrance of the bay, were broken and drifted into the bay as shown in Fig. 1(a). 11523 m3 of oil, mainly heavy oil as well as gasoline and light oil, was released through the way. After the tsunami, 18 tanks were found in different parts of the city, though 4 tanks went missing according to the fire department of Kesennuma city. The furthest drifted tank reached up to 2.4 km from the mouth of Bay. Storage tanks from an oil tank farm in Banda Acech city were displaced a considerable distance from their base as seen in Fig. 1(b) (Reconnaissance Team of JSCE, 2005).

In Sendai City, the tsunami inundation led to drifting of small and empty storage tanks, and collapsed pipes. Since the emergency shutdown valves of pipelines did not work because of the blackout after the earthquake, large amount of oil spilled out into the dike (Zama et al., 2012). Fig. 2 shows the heavy oil spill in dike in Sendai area. The tank was empty when the tsunami struck and submerged into the sea water up to 3.5m high form the bottom plate. The tank did not uplift nor displace even though it was empty. However, the broken pipelines that crossed near the tanks, spilled out oil into the dike (Nishi, 2012).

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