NASA recently reported that its InSight lander — sent to observe geologic activity beneath the Martian surface — recorded one of its biggest quakes yet on Sept. 18. The 4.2 temblor, a quake that would have been big enough for people to feel had it happened on Earth, lasted an hour-and-a-half.
The agency also noted that the 4.2 quake was the third "major" quake InSight has observed in the last month. Both a 4.2 and 4.1 magnitude quake hit on Aug. 25.
InSight landed on Mars in Nov. 2018, so planetary scientists are still observing how geologically active Mars truly is. The solar-powered lander has observed hundreds of quakes, suggesting there might be volcanically active places in the Martian underground, perhaps hot molten rock (magma) moving and flowing like it does on Earth.
Though NASA researchers are still studying the recent September quake, they've found the August marsquakes occurred far off, much farther than where the other quakes originated in the plains of Cerberus Fossae.