Mars very active

The climate on Mars is showing a warming trend and recent images have shown the first evidence of seismic activity on Earth's neighbour planet, scientists said on Tuesday.

New gullies that did not exist three years ago have been pictured on a Mars sand dune - just another of what scientists say are surprising discoveries found by cameras aboard the eight-year-old Mars Global Surveyor that are changing notions about the climate and formation of Mars.

"To see new gullies and other changes in Mars surface features on a time span of a few years presents us with a more active, dynamic planet than many suspected," said Michael Meyer, Nasa's Mars Exploration Program chief scientist.

Images taken by the Mars Orbiter Camera on board the Surveyor showed that boulders have fallen down a Martian slope in the past two years. Michael Malin, principal investigator for the Mars Orbiter Camera, told reporters it was the first evidence scientists had seen of some kind of seismic activity, or possible "marsquake," on the planet.

If so, "it could speak to the planet having warmth in the interior... which means the interior could be more active than previously thought and there could be a habitable environment in the deeper regions of Mars," said Jack Mustard, geological sciences professor at Brown University in Providence, Rhode Island.