A large number of industrial facilities were damaged during the 1999 Mw 7.4 Kocaeli, Turkey earthquake. One of those industrial facilities, Habas plant located within 10 km of the fault trace, provides liquefied gases to commercial plants and medical facilities. Two of the three tanks at the Habas facility collapsed during the earthquake. The main objectives of this paper were to evaluate the seismic performance of tanks and investigate the parameters influencing the dynamic behaviour. Simplified and finite element dynamic analyses of the tanks are carried out including the effect of liquefied gas-structure interaction using a ground motion recorded at a nearby site. The vulnerabilities of the structural system, the observed performance, and damage pattern are discussed by comparing the dynamic analysis results with the strength and deformation capacity of the support columns. The dynamic analysis results from a simplified three-mass model and a finite element model confirmed that the axial and lateral strength of the columns supporting the two nearly full tanks were not sufficient to resist the demand imposed during the earthquake. Consistent with the observed structural performance, an elastic response is predicted for the columns supporting the undamaged 25% full identical tank. © 2008.