Mars used to be a mover and a shaker. Scientists don’t know if it still entertains seismic activity, however. No mission has ever been equipped to properly measure any rattling that might still occur. Now a study comparing images of intriguing pits on Mars to similar features on Earth suggests the red planet indeed still rumbles. “It’s likely that there may be marsquakes today, but seismic monitoring will be required to know for sure,” said study leader David Ferrill of the Southwest Research Institute in San Antonio, Texas. “Until then, it’s just scientific speculation.”