An electrical ablation apparatus comprises first and second electrodes. Each electrode comprises a first end configured to couple an energy source and a second end configured to couple to a tissue treatment region. An energy source is coupled to the first and second electrodes. The energy source is configured to deliver a first series of electrical pulses sufficient to induce cell necrosis by irreversible electroporation and a second series of electrical pulses sufficient to induce cell necrosis by thermal heating, through at least one of the first and second electrodes. The first series of electrical pulses is characterized by a first amplitude, a first pulse length, and a first frequency. The second series of electrical pulses is characterized by a second amplitude, a second pulse length, and a second frequency.