Liquid storage tanks are used to preserve liquids such as oils, water, petrochemical fuels, nuclear fuels, etc. It is crucial to protect these structures against strong dynamic forces, such as earthquakes. For a given structure, the seismic risk is evaluated for a defined damage state, considering the appropriate intensity measure. The selection of intensity measures is crucial, and it is determined by the criteria of efficiency and sufficiency. In this study, an attempt is made to identify optimal intensity measures for liquid storage tank base-isolated by laminated rubber bearing. Here, peak isolator displacement is considered as an engineering demand parameter, and the efficiency and sufficiency analyses are performed for several intensity measures. Additionally, a parametric analysis is carried out by considering different tank slenderness ratios. It is observed that the average spectral acceleration for the broad tank and spectral acceleration at the isolation period for the slender tank are efficient and sufficient intensity measures. These results can be used in assessing the fragility and seismic risk of liquid storage tank base-isolated with laminated rubber bearing.