Probabilistic holistic seismic risk evaluation methodology for port structures

Seaports are the cornerstone of international trade and have become increasingly important as the trend for globalized production and distribution of goods has grown stronger.Seaports are also an important part of transportation networks because they function both as sources and sinks for the freight traffic that flows through the transportation infrastructure of acountry. In the past, ports have suffered serious damages from earthquakes because their locationnear estuaries and river deltas and their construction on landfills has made them particularly susceptible to liquefaction and ground failure. Damage to port structures that reduces theirfunctionality will limit the port’s operational capacity and result not only in monetary lossesattributed to the repair and replacement cost of the structures, but will also result in revenue losses due to reduced throughput. The operational capacity of a maritime port after an earthquakeis of great concern to the port authority and tenants because port revenues and market shareretention depend largely on the continuing operation of the berthing facilities. Moreover, freight movement through the port is important for the local industries and factories. For many regions,a capacity reduction in the port system results in severe economic consequences. Two recent events demonstrate that an earthquake can severely affect port operations. After the1989 Loma Prieta, California, earthquake, one of the 8 container terminals of the Port ofOakland sustained heavy damage and had to cease shipping operations completely. It took almost six months to fully restore operations while the repairs continued. Eventually, the portestimates it spent $14 million (in 1989 dollars) and it took 23 months to inspect, analyze, design,bid, and reconstruct 922m of damaged wharf in that terminal [7]. Fortunately, the ship traffic could be diverted to other operating terminals, so no loss of operating revenues was reported.After the Great Hanshin earthquake in Kobe, Japan in 1995, the direct repair cost incurred by theport of Kobe was estimated to be (in 1995 dollars) $5.5 billion and the economic impacts on port dependent industries due to the loss of operations at the port were estimated to be about $6billion [28]. During the earthquake, the port lost about 80% of its operating capacity due toextensive wharf damage. It was reported [9] that the Port of Kobe had only recovered 80.4% of its monthly amount of exports and imports as compared to before the earthquake. Thispermanent loss of business occurred even though the port had recovered 75% of its cargohandlingcapacity one year later. What is more astonishing in the case of Kobe Port is that, although Japan is a country of earthquakes and during the last 100 years had 185 earthquakeswith Richter magnitude bigger than seven, Kobe had not experienced an earthquake of magnitude bigger than seven in the last thousand years. Thus, the potential for losses to a port2 subjected to an earthquake cannot be ignored but should be evaluated based on the seismicity ofthe region, and mitigation actions should be pursued. Consequently, when authorities plan and design new ports or evaluate and expand existing ones, it is necessary to examine the possiblerepercussion of potential failures due to such extreme events and account for them in their capitalallocation program. In this paper, a probabilistic methodology for evaluation of holistic seismic risk in port structuresis introduced. The results of the model contain the probability of unsafe situations and economic impacts of damages in all levels. The effect of secondary hazards on damages and losses is estimated through probabilistic framework as well.

Probabilistic holistic seismic risk evaluation methodology for port structures Keywords:

seismic risk , direct loss , indirect economic impacts , port , probability