The 2020 Alex storm in southern France led to localized extreme rainfall exceeding 600 mm in less than 24 hr. In the 100 days following the storm, a series of small earthquakes swarm occurred beneath the Tinée valley, a region characterized by a low background deformation. To gain insight into the mechanisms controlling swarm evolution, we used an enhanced seismic catalog to detect 188 events. These events exhibited magnitudes comprised between −1.03 and 2.01, and 78 of them were relocated using relative locations at an average depth of 3–4 km. Additionally, we estimated the directions and velocities of seismicity migration. Our analyses reveal multiple episodes of hypocenter expansion and migration within a fluid‐saturated fault system. Observations provide evidence of a bi‐directional seismicity migration marked by dual velocities within a swarm. The northward seismicity migration aligns with velocities indicative of aseismic slip (∼130 m/hr), while the southward migration corresponds to velocities associated with fluid pressure diffusion (∼5 m/hr). This migration pattern underscores the interplay of multiple physical mechanisms in both triggering and driving earthquakes. A stress‐driven model based on rate‐and‐state friction successfully explains the overall evolution of observed seismicity, whereas a fluid‐driven model fails to reproduce the data. Our observations and models suggest that fluid pressure changes resulting from intense rainfall caused aseismic slip in the shallow portion of the crust. We hypothesize that aseismic deformation serves as the driving force for the earthquake swarms, coupled with the invasion of pressurized fluid due to diffusing rainfall.

The conditions for the transition from slow slip to seismic generation motion along a tectonic fault as a result of fluid injection through a well located near the fault are studied.Movements along the fault caused by fluid injection can occur in the form of slow slips or lead to earthquakes. The implementation of a particular type of movement is dependent on the injection parameters and the fault friction and stress conditions. Numerical calculations were performed in which the consequences of fluid injection lasting from 1.5 months to 6 years were modeled. The calculations varied the total volume of the injected fluid, the flow rate during injection, the rate-state friction law properties of the fault, tangential stresses on the fault. It was found that under certain combinations of fault parameters and fluid flow, seismic generations occur. The transition to such a mode within the framework of the considered model occurs abruptly, a further increase in the injection rate does not lead to an increase in the rate of seismic movement, reaching values of 0.1-1 m/sec, depending on tectonic tangential stresses.With fixed parameters of the rate-state friction law, the magnitude of the maximum displacement velocity depends on the rate of the pressure perturbation on the fault. Until the sliding velocity reaches a value of the order of 10-6 m/sec, the dependence of the logarithm of the sliding velocity on the rate of the pressure perturbation is linear or close to it, then there is a significant more dramatic increase in sliding velocity depending on the rate of the perturbation growth. The influence of the rate-state friction law parameters on the movements along the fault is not so unambiguous. However, it can be said that the sliding is determined by a combination of the following parameters: the critical length at which the stiffness of the fault section reaches the value of critical stiffness, and the characteristic response time determined by the parameters of the friction law.