Schumann resonances are standing waves that oscillate in the electromagnetic cavity formed between the conducting lower ionosphere and the surface of the planet. They have been measured in-situ only on Earth and Titan, although they are believed to exist on other planets like Mars. We report numerical simulations of the Martian electromagnetic cavity, accounting for the day - night asymmetry and different dust scenarios. It has been found that the resonances are more energetic on the nightside, the first resonance is expected to be 9 - 14 Hz depending on the dust activity, and to have low quality factors (Q≃2). This work serves as an input for the upcoming Exomars surface platform (launch 2020), who will attempt to measure them for the first time.