Seismic monitoring system of Baixo Sabor hydroelectric power scheme

Abstract

The Baixo Sabor hydroelectric scheme is located at northeast of Portugal and creates a reservoir with a storage capacity of 630 million m3 of water. The dam is a concrete double-curvature arch dam with 123 m high. According to the Portuguese legislation and considering the seismic risk of the dam construction zone, a Seismic Monitoring System (SMS) need be provided. In their most extensive configuration, these systems may incorporate remote stations along the reservoir for studying the propagation of seismic waves and to detect eventual induced reservoir seismicity. So, for the observation of the seismic activity on the surrounding area of the reservoir, to characterize the seismic action and the corresponding structural response of the dams, an observation system based on triaxial accelerometers was designed and installed. This system has been in continuous operation since its installation, and the data of the recorded earthquake records has been analyzed and processed. This article presents a brief description of the regional geological and tectonic setting including the stratigraphic and lithological unit’s description, the main geological faults, tectonic history resume, and the local geological surface characterization of the seismic exterior stations. Also, the paper describes the main features of the seismic monitoring system that was installed in the Hydropower Scheme of Baixo Sabor, constructed and owned by EDP Produção a company of EDP - Energias de Portugal Group, and presents some of the main results obtained during the first period of operation of the dam.