A currently debated issue in seismology concerns the possible existence of coupling among earthquakes distant in space and time. Here, we provide the results of a simulation that mimics the coseismic and postseismic interactions in a spherical and viscoelastic Earth. In particular, the model estimates the stress induced by remote earthquakes at selected points on the Earth's surface, and the effects on a simple fault model. The obtained results indicate that a seismic zone can interact significantly with other remote seismic regions. Clusters in seismicity, gaps, and nonstationary behavior in general might be induced by the occurrence of large earthquakes at distances up to about 1000 km. These findings suggest that an implied paradigm of seismic hazard studies, i.e., seismic zones are isolated and stationary systems, should be regarded with extreme caution. Finally, we show some empirical evidence of possible long-term interaction in the seismicity of southern California.