Costa Rica is characterized by a high seismicity due to its location in a subduction zone and near to the triple point of the plates Coco, Caribbean and Nazca. This study evaluates the stability of the mean rate earthquake occurrence and the spatial and temporal distribution of seismicity in Costa Rica, in order to calculate the completeness magnitude for the RSN seismic catalog and the Gutenberg-Richter relationship for 1975-2017. Results show that the completeness magnitude for the catalog is 5.0, but it could be as low as 3.0 Mw for certain periods of time. The preliminary “b” value and maximum likelihood magnitude obtained for this catalog are 0.96, and 7.8, respectively. The geographic distribution of seismicity highlights the main active tectonic structures. In particular, clusters of seismicity revels highly deformed crustal areas, which are located along the inland projected path of seamount chains and the Panama Fracture Zone. These clusters do not correlate exactly with the largest energy released zones. These results are vital for understanding the tectonic setting of the region and the correct assessment of the seismic hazard and risk mitigation.