Abstract: The present disclosure describes methods and systems for fracturing geological formations in a hydrocarbon reservoir. One method includes forming a borehole in a hydrocarbon reservoir from a surface of the hydrocarbon reservoir extending downward into the hydrocarbon reservoir; transmitting an electromagnetic (EM) wave through the borehole; directing at least a portion of the EM wave to rocks at a location below the surface in the hydrocarbon reservoir; and fracturing the rocks at the location below the surface in the hydrocarbon reservoir by irradiating the rocks around the borehole using at least the portion of the EM wave, where the irradiating is performed by irradiating a first portion of the rocks by using the EM wave for a first duration and after irradiating the first portion of the rocks for the first duration, refraining from irradiating the first portion of the rocks for a second duration.