A method and device for monitoring a subsoil zone, wherein a plurality of receivers are arranged on a surface of the soil or near said surface, straight above a geological zone to be monitored, comprising the following steps: generating a set of reference seismic data; recording seismic data by means of said receivers; correlating the seismic data recorded with the reference seismic data; comparing each trace of the correlated data, with correlated traces located in a vicinity of said trace, in order to evaluate a similarity of each correlated trace with the adjacent correlated traces; and, detecting a microseismic event occurring in the subsoil zone by analysing said similarity. The method and device enables real-time monitoring.