It is not ruled out there are active volcanoes on Mars nowadays
Volcanic activity was happening on Mars much later than scientists first thought. The European Space Agency's Mars Express spacecraft determined Martian volcanoes could be active from one to twenty million years ago. According to previously collected data, the volcanic activity on Mars stopped at least 500-600 million years ago. Some researchers talk about the possibility of active volcanoes on Mars nowadays. Pursuant to the new information, some Martian volcanoes can be very young.
The stereo camera on board Mars Express photographed three 15-km high volcanoes on Mars in the Tarsis area – Olympus Mons and three other great volcanoes. According to experts' estimates, the volcanic activity on Mars continued in the Tarsis area even when the whole planet faded.
Speaking about the possible volcanic activity in our times, it may not necessarily manifest itself in eruptions, if it really exists, ESA Mars Express Project Scientist, Augustin Chicarro, believes. However, the existence of small volcanoes is not excluded either. Scientists do not hope to find active volcanoes on Mars. The maximum of what they expect to discover is an indication of hydrothermal activity.