Unstructured finite-element methods are widely used in earthquake simulations for accurate modeling of complex three-dimensional geometry and nonlinear material properties. However, its applicability to large-scale problems is often limited by the difficulty of generating high quality mesh and large analysis cost. To overcome these difficulties, we have been developing robust mesh generators and fast analysis methods in an integrated approach. In this talk, I will show Tera Degrees-of-Freedom scale unstructured finite-element earthquake simulations enabled by using the developed method on the full K computer.