AbstractForeshock activity sometimes precedes the occurrence of large earthquakes, but the nature of this seismicity is still debated, and whether it marks transient deformation and/or slip nucleation is still unclear. We here study at the worldwide scale how foreshock occurrence affects the postseismic phase and find a significant positive correlation between foreshock and aftershock activities: earthquakes preceded by accelerating seismicity rates produce 40% more aftershocks on average, and the length of the aftershock zone after 20 days is 20% larger. These observations cannot be reproduced by standard earthquake clustering models that predict the accelerating pattern of foreshock occurrence but not its impact on aftershock activity. This strongly suggests that slow deformation transients, possibly related to episodic creep, could initiate prior to the main shock and extend past the coseismic phase, resulting in compound ruptures that include a very long period (up to tens of days) component.