A method for fracturing a geological hydrocarbon reservoir, in which the method comprises: - a static fracturing (S 20) of the reservoir by hydraulic pressure, and - an electrical fracturing of the reservoir by generating electric arcs in a well drilled in the reservoir; characterised in that the static fracturing precedes the electrical fracturing and in that the electrical fracturing is generated by a device for fracturing which comprises: - two sealing packers (102, 103) defining between them a confined space in a well drilled in the reservoir; - a pump for increasing the pressure of a fluid in the confined space; - an apparatus for heating the fluid; - at least one pair of two electrodes arranged in the confined space; and - an electric circuit for generating electric arcs between the two electrodes, the circuit comprising: - at least one voltage source (112, 118) connected to the electrodes and comprising a capacitor; - an inductance coil between the voltage source and one of the two electrodes; - a Marx generator between the capacitor and the inductance coil to generate a supersonic electric arc between the two electrodes; and - ferrites forming a saturable inductance and a spark gap, the ferrites and the spark gap being disposed on a same branch of the circuit and extending parallel to the Marx generator between the capacitor and the inductance coil to generate a subsonic electric arc between the two electrodes, wherein the circuit successively generates the supersonic electric arc and the subsonic electric arc; and wherein the electrical fracturing comprises generating several arcs in succession, said arcs inducing a pressure wave the rise time of which is decreasing, and the arcs in succession induce a pressure wave whose rise time is less than 100 μs. - a static fracturing (S 20) of the reservoir by hydraulic pressure, and - an electrical fracturing of the reservoir by generating electric arcs in a well drilled in the reservoir; - two sealing packers (102, 103) defining between them a confined space in a well drilled in the reservoir; - a pump for increasing the pressure of a fluid in the confined space; - an apparatus for heating the fluid; - at least one pair of two electrodes arranged in the confined space; and - an electric circuit for generating electric arcs between the two electrodes, the circuit comprising: - at least one voltage source (112, 118) connected to the electrodes and comprising a capacitor; - an inductance coil between the voltage source and one of the two electrodes; - a Marx generator between the capacitor and the inductance coil to generate a supersonic electric arc between the two electrodes; and - ferrites forming a saturable inductance and a spark gap, the ferrites and the spark gap being disposed on a same branch of the circuit and extending parallel to the Marx generator between the capacitor and the inductance coil to generate a subsonic electric arc between the two electrodes, - at least one voltage source (112, 118) connected to the electrodes and comprising a capacitor; - an inductance coil between the voltage source and one of the two electrodes; - a Marx generator between the capacitor and the inductance coil to generate a supersonic electric arc between the two electrodes; and - ferrites forming a saturable inductance and a spark gap, the ferrites and the spark gap being disposed on a same branch of the circuit and extending parallel to the Marx generator between the capacitor and the inductance coil to generate a subsonic electric arc between the two electrodes,