Abstract-In this paper, a hybrid measurement-and modelbased method is proposed which can estimate the dynamic state Jacobian matrix and the dynamic system state matrix in near real-time utilizing statistical properties extracted from PMU measurements. The proposed method can be used to detect and identify network topology changes that have not been reflected in an assumed network model. Additionally, an application of the estimated system state matrix in online dynamic stability monitoring is presented.Index Terms-dynamic state Jacobian matrix, dynamic system state matrix, phasor measurement units, topological error identification, online dynamic stability monitoring