Abstract: In order to study seismic responses and collapse mode of a wind turbine tower under operational conditions, a wind turbine tower model was developed by the wind turbine design software FAST. The structural responses in idle condition and operational conditions were calculated and compared. The influences of different angles between wind and earthquake inputs on structural responses were investigated. A detailed finite element model of the same tower was developed with ABAQUS. Wind load effects induced by the blades were calculated by FAST simulations and were verified with the results estimated through the blade element theory. Elastic analysis results from the FAST model and the ABAQUS model were also compared for verification purposes. Tower collapse simulations were conducted under earthquake excitations using the ABAQUS model. Study results show that the case with a 90° angle between the wind and earthquake inputs is the most dangerous scenario that could occur for tower dynamic responses. Collapse simulations indicate that the plastic hinges are initiated from the bottom part of the tubular tower wall; later, they develop into the upper part of the structure too. The tower fails at the middle-upper part of the tower wall.