Mitigation of seismic and meteorological hazards to marine oil terminals and other pier and wharf structures in California

摘要

For the past 12 years, the California State Lands Commission has been involved in the operational monitoring, structural inspection and requalification of 45 marine oil terminals along California's coast, which have an average age of about 50 years and plans to keep these structures in service for another 20-40 years. Having seen the port and harbor damage from the 1995 Kobe and 1999 Izmit earthquakes, the potential for a major disruption in petroleum product production is real. Losing the daily gasoline production for a period of weeks or months as a result of a moderate earthquake or tsunami could significantly affect the economic well being of California and much of the western United States. In addition, a major oil spill resulting from such anevent could cause the closure of a major port for days or even weeks. Such a closure would further affect the economy of California and the United States. Most of these facilities were designed to primitive seismic standards and for vessels much smallerthan those currently moored. Many of these structures have never had a comprehensive underwater inspection. Wind and current forces on large tank ships can cause mooring lines to break or cause serious structural damage to supporting structures. In California, non-regulatory progress has been made in the following areas: (i) underwater and above water inspections or audits; (ii) mooring analyses and structural/environmental monitoring in high velocity current areas; (iii) seismic analyses and structuralrehabilitation with updated seismic hazard data; and (iv) accelerometers on marine structures. In addition, standards have been developed and are proposed to be regulatory by early 2004. The new standards include most of the items listed above, but alsoextend into many other areas. Along with the proposed regulations come many issues that raise economic and political questions. These issues are not unique to marine oil terminals and are applicable to other pier and wharf structures in harbors.