Power grids are prone to damage induced by natural or anthropogenic hazard events that might disrupt the functionality of key/multiple grid components concurrently, resulting in a chain of cascade failures spreading throughout the grid. Through integrating grid operation-guided with structure-driven modeling strategies, the current study proposes an approach to manage the risks of such cascade failure (known as systemic-risks) to minimize the possibility of large-scale catastrophic blackouts. The operation-guided modeling strategy is implemented through dispatch and load shedding to rebalance power demand and supply after disruptive events. On the other hand, the grid structure-driven modeling strategy adopted intentional controlled islanding approach through employing a constrained spectral clustering algorithm. Introducing the latter algorithm within the integrated (operation + structure) cascade failure model facilitated identifying the optimal cut-set lines to separate the grid into a group of functioning sub-grids following initial failure and prior to cascade propagation. To demonstrate the utility of the developed systemic risk management strategy, an actual power grid was simulated using a high-fidelity physics-based model under different disruption scenarios to compare the cascade failure size with and without strategy implementation, considering different numbers of sub-grids. The simulations demonstrate that the integrated (dispatch & load shedding-controlled islanding) strategy can effectively boost the overall grid robustness, and subsequently its resilience, and effectively manage catastrophic blackout systemic risks.