We use the seismic signals of 1800 local earthquakes and the continuous signal recorded at the nearest station for the 6 years preceding the mainshock. The preseismic phase depicts a long-term increase of seismicity rate and several bursts of micro-earthquakes. The longest swarm occurs one month before the Gorkha earthquake, lasts one week and consists of 38 repetitive earthquakes located at the north western edge of the rupture zone. It is followed by another increase in seismicity rate which starts six days before the mainshock and includes small foreshocks that develop at less than 10 kilometers from the future earthquake hypocenter. These observations suggest that the Gorkha earthquake was preceded by a pre-seismic phase related to a potential initiation of a slow slip with fluids implicated at the northwestern boundary of the rupture zone.