This article describes the Cahora Bassa dam's SSHM system (Seismic and Structural Health Monitoring System) installed in 2010 to measure and analyse the dam's vibrations, and describes the two upgrades it has undergone, implemented in 2013 and 2024. The original SSHM system, installed in 2010, consisted of ten uniaxial accelerometers in the dam's crown gallery. In 2013, three more triaxial accelerometers were installed at the dam-foundation interface, two near the abutments and one near the base of the central section. This system has provided valuable data on the dam's dynamic properties, such as natural frequencies and mode shapes, which are extracted using modal identification software specifically developed for the Cahora Bassa dam. Recently, in 2024, the SSHM system of the Cahora Bassa dam was upgraded through the installation of five additional uniaxial accelerometers in the dam's second gallery. With the addition of these five new accelerometers, the software for modal identification and dynamic behaviour evaluation required some adjustments that are described. These new accelerometers aim to enhance the accuracy of modal analysis, offering a more detailed identification of the dam dynamic characteristics. By comparing historical data with the newly acquired measurements, we expect improvements in the precision of mode shape and natural frequency estimations. The updated system (equipment and software) is expected to provide a deeper insight into the structural behaviour of the dam.